The TFPRiD and AM Vehicons are almost the same, slight cosmetic differences due to the former using paint apps/tampos and the latter being more reliant on stickers. Also different weapons; AM comes w/ the Arms Micron weapon.
FE Vehicon is an
entirely different mould altogether. Far less shellformery than TFPRiD/AM Vehicon with a more complex transformation/design. FE is also larger, which isn't surprising considering that we've seen downsizing across the board with TFPRiD moulds compared to their FE counterparts.

FE Vehicon also has a pistol rather than a rifle, which 'replaces' the hand and makes it look more like the cartoon.
I've posted comparison pics
here