vegetarian vs eater

vegetarian and eater both are nouns.

Word	Noun	Adjective	Verb	Adverb
vegetarian	Yes	No	No	No
eater	Yes	No	No	No

As nouns, eater is a hypernym of vegetarian; that is, eater is a word with a broader meaning than vegetarian:

vegetarian: eater of fruits and grains and nuts; someone who eats no meat or fish or (often) any animal products
eater: someone who consumes food for nourishment

Other hypernyms of vegetarian include feeder.

vegetarian (noun)	eater (noun)
eater of fruits and grains and nuts; someone who eats no meat or fish or (often) any animal products	any green goods that are good to eat
	someone who consumes food for nourishment