steak vs fish steak

steak and fish steak both are nouns.

Word	Noun	Adjective	Verb	Adverb
steak	Yes	No	No	No
fish steak	Yes	No	No	No

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

Other hyponyms of steak include beefsteak, medallion.

steak (noun)	fish steak (noun)
a slice of meat cut from the fleshy part of an animal or large fish	cross-section slice of a large fish