lemon sole vs flounder

lemon sole and flounder both are nouns.

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

As nouns, flounder is a hypernym of lemon sole; that is, flounder is a word with a broader meaning than lemon sole:

lemon sole (noun)	flounder (noun)
small European sole	any of various European and non-European marine flatfish
European flatfish highly valued as food	flesh of any of various American and European flatfish
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

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