walk-in vs defector

walk-in and defector both are nouns.

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

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

walk-in: an operative who initiates his own defection (usually to a hostile country) for political asylum
defector: a person who abandons their duty (as on a military post)

Other hypernyms of walk-in include deserter, intelligence agent, intelligence officer, operative, secret agent.

walk-in (noun)	defector (noun)
a small room large enough to admit entrance	a person who abandons their duty (as on a military post)
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)	defector (adjective)
(of e.g. closets or refrigerators) extending very far enough back to allow a person to enter