great vs achiever

great and achiever both are nouns.

Word	Noun	Adjective	Verb	Adverb
great	Yes	Yes	No	No
achiever	Yes	No	No	No

As nouns, achiever is a hypernym of great; that is, achiever is a word with a broader meaning than great:

Other hypernyms of great include succeeder, success, winner.

great (noun)	achiever (noun)
a person who has achieved distinction and honor in some field	a person with a record of successes

great (adjective)	achiever (adjective)
excellent
in an advanced stage of pregnancy
uppercase
remarkable or out of the ordinary in degree or magnitude or effect
of major significance or importance
relatively large in size or number or extent; larger than others of its kind