Offhand, no difference except number change..haha...
bad joke..
Seriously, not much change in the cab robot - the same red and blue color scheme except for the Autobot logo imprinted on the right leg of the G2 Prime.
G1 Optimus Prime (top), G2 Optimus Prime (bottom). Notice the imprinted logo on the leg?
However, G2 trailer is now black in color instead of silver, with red sticker bearing the name "Optimus Prime" in place of the blue and silver striped one.
G2 Prime is more heavily armed, now with 2 black missile launchers which fire spring-loaded missiles - a lot more play value as compared to its G1 brother.
G1 Optimus Prime (back), G2 Optimus Prime (front). Distinct difference in trailer color and accessories.
I would say G2 Prime is a rare find nowadays, with MISB-conditioned box selling above RM500. If you really look around, you might find loose complete ones here and there. Most frequent find are those which are incomplete, usually missing its missiles, nozzle, fuel pump and/or hose. Fortunately, the nozzles, hose and pump do not affect transformation but for a collector, it's always a good feel to have a complete set...
