Model Number Explanation

Hello to the community!

I would like to buy the MacBook Pro 2017 13" NO touch bar (Model identifier: MacBookPro14.1 - A1708 )

but searching on the site I found this model numbers list:

MPXQ2LL / A

MPXR2LL / A

MPXT2LL / A

MPXU2LL / A

What do they mean?

They indicate different models with different processors/colors or are just shipping codes used by Apple?

Please could you help me? Thanks in advance!