answer vs fulfil

answer is a noun but fulfil is not a noun.

Word	Noun	Adjective	Verb	Adverb
answer	Yes	No	Yes	No
fulfil	No	No	Yes	No

As verbs, fulfil is a hypernym of answer; that is, fulfil is a word with a broader meaning than answer:

answer: be satisfactory for; meet the requirements of or serve the purpose of
fulfil: fill, satisfy or meet a want or need or condition or restriction

Other hypernyms of answer include conform to, fill, fit, fulfill, meet, satisfy.

As verbs, fulfil is a hypernym of answer; that is, fulfil is a word with a broader meaning than answer:

Other hypernyms of answer include fulfill, live up to, satisfy.

answer (noun)	fulfil (noun)
a nonverbal reaction
the speech act of replying to a question
a statement (either spoken or written) that is made to reply to a question or request or criticism or accusation
a statement that solves a problem or explains how to solve the problem
the principal pleading by the defendant in response to plaintiff's complaint; in criminal law it consists of the defendant's plea of `guilty' or `not guilty' (or nolo contendere); in civil law it must contain denials of all allegations in the plaintiff's complaint that the defendant hopes to controvert and it can contain affirmative defenses or counterclaims

answer (verb)	fulfil (verb)
give the correct answer or solution to	fill, satisfy or meet a want or need or condition or restriction
respond to a signal	put in effect
understand the meaning of	meet the requirements or expectations of
react to a stimulus or command
react verbally
give a defence or refutation of (a charge) or in (an argument)
be satisfactory for; meet the requirements of or serve the purpose of
match or correspond
be liable or accountable
be sufficient; be adequate, either in quality or quantity