ambusher vs assailant

ambusher and assailant both are nouns.

Word	Noun	Adjective	Verb	Adverb
ambusher	Yes	No	No	No
assailant	Yes	No	No	No

As nouns, assailant is a hypernym of ambusher; that is, assailant is a word with a broader meaning than ambusher:

ambusher: an attacker who waits in a concealed position to launch a surprise attack
assailant: someone who attacks

Other hypernyms of ambusher include aggressor, assaulter, attacker.

ambusher (noun)	assailant (noun)
an attacker who waits in a concealed position to launch a surprise attack	someone who attacks