besieger vs enemy

besieger and enemy both are nouns.

Word	Noun	Adjective	Verb	Adverb
besieger	Yes	No	No	No
enemy	Yes	No	No	No

As nouns, enemy is a hypernym of besieger; that is, enemy is a word with a broader meaning than besieger:

besieger: an enemy who lays siege to your position
enemy: an armed adversary (especially a member of an opposing military force)

Other hypernyms of besieger include foe, foeman, opposition.

besieger (noun)	enemy (noun)
an enemy who lays siege to your position	an opposing military force
an energetic petitioner	any hostile group of people
	an armed adversary (especially a member of an opposing military force)
	a personal enemy