I think Charles documented almost all of the differences in a post some months back.
The question of wheel pant vs. mounting plate vs. axle mounting is a little more complex than most folks realize. There are several bolt spacings available on the flat gear axles, therefore axles/mounting plate combinations are not always interchangeable with gear legs, let alone wheel pants. I'm pretty sure any 150/152 round gear leg mounting plate will fit any other round gear leg mounting, but will not fit any flat gear mounting. I think all of the mounting plates are made of flat stock, so in theory, any wheel pant can be made to fit any axle bolt pattern by fabricating a custom set of mounting plates from flat stock, but then the whole installation will require FAA approval. Aircraft Spruce and probably others now offer new PMA'd mounting plates, but not for all models. Simply drilling (elongating) new mounting holes where required might work, but might also weaken the mounting, and obviously isn't authorized by p/n either.
