bitterness vs hostility

bitterness and hostility both are nouns.

Word	Noun	Adjective	Verb	Adverb
bitterness	Yes	No	No	No
hostility	Yes	No	No	No

As nouns, hostility is a hypernym of bitterness; that is, hostility is a word with a broader meaning than bitterness:

Other hypernyms of bitterness include enmity, ill will.

bitterness (noun)	hostility (noun)
the property of having a harsh unpleasant taste	violent action that is hostile and usually unprovoked
a rough and bitter manner	a hostile (very unfriendly) disposition
the taste experience when quinine or coffee is taken into the mouth	the feeling of a hostile person
a feeling of deep and bitter anger and ill-will	a state of deep-seated ill-will