defend vs prevent

defend and prevent both are verbs.

Word	Noun	Adjective	Verb	Adverb
defend	No	No	Yes	No
prevent	No	No	Yes	No

As verbs, prevent is a hypernym of defend; that is, prevent is a word with a broader meaning than defend:

defend: be on the defensive; act against an attack
prevent: stop (someone or something) from doing something or being in a certain state

Other hypernyms of defend include keep.

defend (verb)	prevent (verb)
argue or speak in defense of	stop (someone or something) from doing something or being in a certain state
state or assert	keep from happening or arising; make impossible
be on the defensive; act against an attack
protect against a challenge or attack
protect or fight for as a champion
fight against or resist strongly
be the defense counsel for someone in a trial