flounder vs lemon sole

flounder and lemon sole both are nouns.

Word	Noun	Adjective	Verb	Adverb
flounder	Yes	No	Yes	No
lemon sole	Yes	No	No	No

As nouns, lemon sole is a hyponym of flounder; that is, lemon sole is a word with a more specific, narrower meaning than flounder:

Other hyponyms of flounder include yellowtail flounder, plaice, turbot, sand dab, winter flounder.

flounder (noun)	lemon sole (noun)
any of various European and non-European marine flatfish	small European sole
flesh of any of various American and European flatfish	European flatfish highly valued as food
	important American food fish in the winter
	popular pale brown food flatfish of the Pacific coast of North America
	highly valued almost pure white flesh
	flesh of American flounder; important in the winter

flounder (verb)	lemon sole (verb)
walk with great difficulty
behave awkwardly; have difficulties