The earliest version, as shown in the first patent application for the toy, was to have the Prime cab be a triplechanger, turning from truck cab to jet or robot. The nosecone of the jet and robot legs were released by the Powermaster lock in the same fashion as the legs in the final version. Optimus would have had winged arms in non-super robot mode. The super robot mode's head was also integrated into the trailer's hitch... and lacked a faceplate.
The "Underbite Jetpack Takedown" Optimus Kreon uses the new 2015 style of Kreon hips and torso, with a hollow hip-peg and a central post inside the torso for increased grip... which also makes them incompatible with about four years' worth of Kreons. Based on his appearance in Robots in Disguise, he features a new version of the Optimus helmet, this time lacking a moutplate. He attaches to an included jet pack, armed with two pressure-launch missiles.
I agree with Aidan but would expand on his point. It’s not just that the sets seemed bigger; they were. As the relative complexity of sets has increased, so too has the piece count, but there has been an overall decline in the size of the models due to increased build complexity and a corresponding reduction in size of the pieces required to create such detail. The negative affect on perceived value in this is apparent, though I would argue, misguided when one considers the build quality and detail of new and recent sets.
The two sides found themselves equally matched until the Constructicons merged into The Devastator. The tables were turned once more when the Dinobots appeared, and mercilessly slaughtered the Constructicons. The Decepticons' plan foiled, Optimus decided that the Autobot-Decepticon war had come to an end, despite Megatron's protests to the contrary. He and his Autobots then drove away victorious. Battle for Earth
The conclusion to the storyline was forestalled when Hasbro retracted 3H Enterprise's license, but an explanation can be found in issue 8 of the Transformers Collectors Club magazine, Cybertron/Robots in Disguise. In this issue, Prime tells the tale of how Unicron's forces were defeated in the last battle by Optimus Primal's forces and Unicron disappeared into the black hole opened in Transformers: Energon. Combined as Omega Prime, they could not escape fast enough, and were sucked into another dimension.
This straight reissue of the original Optimus Prime figure was released in Hasbro's European markets in the early 1990s, at the same time as many other Generation 1 figures were being re-released as "Classics". Oddly, although he shares their golden packaging, Prime is not actually identified as a "Classics" figure anywhere on his box, but is generally considered to be part of the sub-line for simplicity's sake.
This golden chromed redeco of the Super class Optimus Prime figure was initially offered as a prize to five lucky winners of a colouring contest held in the pages of the TV Magazine. Additional units were later given away via in-store draws at Toys"R"Us Japan; precisely how many is unknown, but the regularity with which the toy appeared on auction sites throughout 2005 suggests it was quite a few.
Part of the first wave of Transformers: Robots in Disguise Hyperchange Heroes, Optimus Prime transforms from a futuristic trailer truck to robot in just 3 easy steps! His arms & legs serve as his trailer, while his chest serves as his truck front. He is also one of the few Robots in Disguise Optimus Prime toys which does not feature a faux window chest in robot mode. Both of his arms are articulated with 5mm holes in each hand.
Millions of years later, Optimus was one of the thirty-five Autobots rebuilt into modern machines by the ship"s computer. Some time later, Jazz reported that he had spotted Decepticon activity at a nearby construction site. Optimus decided to take a proactive angle to their war with the Decepticons, and led the entirety of his troops to the Decepticon base. Once there, they found themselves allowed in by Megatron, feigning a friendly demeanor. Not fooled by Megatron's claims that he was making an honest living heading a construction company, Optimus engaged the evil robots in combat, before being blasted out of the Decepticon base. Optimus and his troops were sent tumbling down the cliffside beneath their feet. The Autobots suffered only minor damage from the fall, and after getting patched up, moved out once more to stop Megatron's plan, now well under way. Megatron was holding millions of humans hostage in a bid to get the Earth to surrender unconditionally to the Decepticons.
When the Decepticons tried to take control of a solar energy station, Prime sent Roller in to investigate. Megatron's Fight for Power Later, Prime sent Bumblebee to spy on the Decepticons' latest misdeeds, and the Autobots discovered that they were having trouble with the ion drive of their starship. Prime led the Autobots in an attack on the mine the Decepticons were using to test their propulsion system and routed Megatron's force. Autobots Fight Back
Just as Marvel Comics produced a companion comic to the original Transformers toyline that differed from its animated counterpart, so did Dreamwave produce a comic to go along with the Transformers: Armada and Energon lines that owed little to their animated fellows. This incarnation of Optimus Prime, however, is not particularly different from his animated counterpart in personality.
Some time later, as the war raged between Autobots and Decepticons on Earth, Optimus had requested the Aerialbots as reinforcements from Cybertron. Though they nearly defected to the Decepticons, Optimus was able to secure the Aerialbots as allies. Later, when a power plant had to be evacuated of its human workers due to the fear of landslides, Optimus posted Denfensor at the location to secure its protection. Optimus then drove off to check up on the rest of his troops who were aiding in the area’s evacuation. Though he passed a military convoy heading towards a plant, he thought nothing of it, unaware that they were the newly created Combaticons in disguise. Optimus then reached the Ark, and from there opened communications with the Aerialbots. Optimus had someone come into the know that the Decepticons were moving in towards the plant. He watched from afar as Defensor and Superion fought Menasor and Bruticus, wary to send more Autobots into the fray while these titans wreaked havoc onto the battlefield. Optimus allowed himself a smile when the Aerialbots and the Protectobots proved themselves superior teams to the Decepticons’, though at the back of his mind, he was wary. After all, Megatron himself had chosen not to add his considerably weight to the battle... The Special Teams
Commander class figures all come with translucent weaponry, and feature some amount of translucent plastic in their bodies (blue for Autobots, but a variety of colors for Decepticons), a feature designed around interacting with the line's vehicles (see below). Each vehicle is equipped with an "Energon Booster", a light-up accessory that can plug into the Commanders' weapons or into the posts and ports on the figures' backs to illuminate them with "glowing energon power".
The energy of the explosion absorbed by the virus, the Autobots dug themselves out and set about recovering their fellows whom Megatron had used to power the cyber-virus in its early stages. Ironhide passed on a message from Megatron — there was a surprise in store for the Autobot leader. Optimus and some Autobots including Superion sped to San Francisco, where Megatron had unleashed Devastator. As Prime battled Megatron, he took time to save three humans who were threatened by falling debris, only for the humans to turn on him. The defeat of Superion turned the tide of the battle against the Autobots. Prime Directive #4
In one reality, while the Autobots were boarding the Ark, Optimus voiced his lack of confidence in his leadership, before welcoming aboard Geosensus, who was incapable of transforming to robot mode. Four million years later, Prime and Prowl found the Ark was under attack and defended it with deadly force. In examining the wreckage of the attackers, they realised that the robot Optimus had destroyed was not a Decepticon but Geosensus, who had forced himself to transform in an attempt to fight off the Decepticons. Though Prime was willing to take the rap, Prowl insisted on covering up the mistake to protect Optimus's image as a leader. Parts
Main event time! Nitro figures are more like your traditional Generations/Power of the Primes deluxe bots. Standing at 7-inches, they feature increased detail, additional paint applications and all come with a core to unlock additional features. In addition to Barricade, Optimus Prime, and VW Bumblebee (this one’s my favorite of the entire line), the Nitro series will also have a Camaro ‘Bee.
The 1984 and 1985 toy lines contained several figures of note. Megatron, the Decepticon leader, originally transformed into a realistic Walther P38 pistol with stock and barrel extensions and scope. The Megatron toy was delayed till 1985 for release in the UK. The Constructicons were the first "gestalt" team in the Transformers line, but were different from most subsequent gestalt teams in that they consisted of six members instead of five. The Autobot Jetfire was repainted from a Macross toy, specifically the VF-1 Valkyrie, and the character was renamed Skyfire in the animated television series program for copyright reasons.
Prime is loaded with a ridiculous number of features and accessories. The robot itself is highly poseable, and both the smokestacks on Prime's shoulders and the fuel tanks on his legs can be rotated forward to act as guns, even featuring sculpted detail to this effect. As ever, he comes with a trailer that opens up into his crazy-detailed Combat Deck, featuring more action features than ever before. In trailer mode alone, it features a flip-down support stand so it can stand alone, a spring-loaded pop-out ramp instead of a fold-down one, and when the trailer is split for transformation, the traditional support legs underneath automatically swing out into place. The trailer houses most of Prime's accessories, including his ion blaster (with a moveable ammo clip to allow for multiple poses) and energon-axe, as well as his classic gas pump accessory, now with a poseable wire instead of a rubber hose. Two fold-out compartments provide storage space for six of Prime's interchangeable fists, while the other two remain attached the robot: two clenched, two open, a pointing right fist, a tilted left fist (for holding the ion blaster's ammo clip), and two fists with slots to grip the miniscule Matrix of Leadership that fits in a tiny chamber in Prime's chest. The Combat Deck's artillery robot features two flip-out handles that Prime can grip as if aiming the drone's guns, and Roller is also included, with three different 3mm ports to hold Prime's gun and gas pump. Lastly, Prime comes with a rocket pack like those used by the Autobots in such Generation 1 cartoon episodes as "Dinobot Island", and a stand shaped like the Autobot insignia that allows him to be displayed in mid-air, as if in flight. The rocket pack also has 3mm ports for Prime's weapons, and stores on the front of the trailer in vehicle mode.
The second known version  ditched the triplechanging gimmick on the cab and simplified things a good bit. This Powermaster Prime has several distinct characteristics only seen in the second design, such as the wider "block head" and two faux smokestacks on top of either shoulder as opposed to one. Also, in a rather odd twist, this design features a black head and fists for both super and regular modes rather than the traditional blue. It also had yellow eyes in either mode a la the original Optimus Prime.