Prerequisite can be used as both a noun and an adjective, requirement is a noun.

What do you choose:

Being able to drive is one of the ....... of the job of salesman.

A-prerequirements

B-prerequisites

C-prescriptions

And the answer is B. I don't know exactly why they choose it :(

  There are few to no   "differences"  between synonyms.

They are words with   equivalent meanings.