walk-in vs doer

walk-in and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
walk-in	Yes	Yes	No	No
doer	Yes	No	No	No

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

Other hypernyms of walk-in include actor, worker.

walk-in (noun)	doer (noun)
a small room large enough to admit entrance	a person who acts and gets things done
an assured victory (especially in an election)
an operative who initiates his own defection (usually to a hostile country) for political asylum
person who walks in without having an appointment

walk-in (adjective)	doer (adjective)
(of e.g. closets or refrigerators) extending very far enough back to allow a person to enter