marksman vs deadeye

marksman and deadeye both are nouns.

Word	Noun	Adjective	Verb	Adverb
marksman	Yes	No	No	No
deadeye	Yes	No	No	No

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

Other hyponyms of marksman include franc-tireur, rifleman, sniper.

marksman (noun)	deadeye (noun)
someone skilled in shooting	(nautical) a round hardwood disk with holes and a grooved perimeter used to tighten a shroud
	a dead shot