Crab vs doer

Crab and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
Crab	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of Crab; that is, doer is a word with a broader meaning than Crab:

Other hypernyms of Crab include actor, worker.

Crab (noun)	doer (noun)
the fourth sign of the zodiac; the sun is in this sign from about June 21 to July 22	a person who acts and gets things done
(astrology) a person who is born while the sun is in Cancer