Both come packaged in robot mode so to make a change we'll start there.
Optimus Prime is your basic G1 Optimus Prime design. Or a cheap rip off there off. The colours on the whole toy is too pale and plasticy for a start. The head is too long and stretched out for Prime - the eyes especially which are picked out in a pinkish lilac lightpipe. The knees look like an unnecessary copyright dodging add on here. His hands have headlights on the reverse of them. And don't get me started on the action feature - I showed the back of the box to Liz in the car, said "Oh look disco dancing Prime !" and she was greatly amused. A push in crank handle at the back causes Prime's upper body - everything north of the grill on the front to spin round. It's poor for so many reasons but here's two to be going on with: You can't lock the upper body in place so it just wobbles around, Prime shouldn't have a joint there, it would be more appropriate below the grill. On the plus side..... well the detail in the legs is quite nice. The articulation - knees, swivel below hip, ball jointed hip, universal jointed shoulder, bicep, elbow and neck + action feature mid chest - is adequate enough. The cab has moulded seats inside which looks good. The gun is very nice - transforming to mount on the truck it looks a little like those machine guns with the round cartridge underneath. An oddity on the toy has Prime's wheels sticking out the sides of his chest.
The TF is relatively standard Prime with a few funnies: Remove the gun and then lock the legs together, bend the feet down and then pull the waist down and forwards - this releases the sides of his lower torso which fold down with the wheels - so Prime has sort of ended up in a sitting position. Rotate Prime's body just below the grill 180 degrees - this joint has been previously locked by the body sides with the wheels attached. Fold the fists inwards, bend the elbows, fold the shoulders back and then rotate the arms sideways to lock into the sides of the vehicle. Rotate head 180 degrees and fold down. Take the gun, pull down on the handle so it ends up under the middle of the gun. Fold back the base and peg into Prime's legs
The resulting Truck is about as rough an approximation of G1 Prime as the RM version is. But a bit bigger. Proportionately it's longer - there's no way of collapsing the legs, and with the waist projecting from the back of the cab that adds to the length. Unfortunately this arrangement isn't very stable either, mine flexes quite a bit at all the joints - forward of the waist, hips and knees. There's the back of the head sticking out the top of the cab. Hmmmm. The gun once again is nice - rotating around half way up it's length it looks like a machine gun nicked from another toy.
One day Hasbro will do a G1 Prime Cab right - hopeful the same day they do it with a Trailer that turns into an articulated version of the Power Master form armour. This isn't the G1 Prime replica you want. The gun is the best thing on it and that's not even a G1 accurate one.
To the great surprise of many Optimus Prime and Megatron did later show up as individually carded items in TRU UK nearly a year after the Classics line ended !