detective vs gumshoe

detective and gumshoe both are nouns.

Word	Noun	Adjective	Verb	Adverb
detective	Yes	No	No	No
gumshoe	Yes	No	No	No

As nouns, gumshoe is a hyponym of detective; that is, gumshoe is a word with a more specific, narrower meaning than detective:

Other hyponyms of detective include dick, hawkshaw, plainclothesman, tracer.

detective (noun)	gumshoe (noun)
a police officer who investigates crimes	a waterproof overshoe that protects shoes from water or snow
an investigator engaged or employed in obtaining information not easily available to the public	someone who is a detective