enmity vs bitterness

enmity and bitterness both are nouns.

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

As nouns, bitterness is a hyponym of enmity; that is, bitterness is a word with a more specific, narrower meaning than enmity:

enmity (noun)	bitterness (noun)
the feeling of a hostile person	the property of having a harsh unpleasant taste
a state of deep-seated ill-will	a rough and bitter manner
	the taste experience when quinine or coffee is taken into the mouth
	a feeling of deep and bitter anger and ill-will