salad green vs endive

salad green and endive both are nouns.

Word	Noun	Adjective	Verb	Adverb
salad green	Yes	No	No	No
endive	Yes	No	No	No

As nouns, endive is a hyponym of salad green; that is, endive is a word with a more specific, narrower meaning than salad green:

Other hyponyms of salad green include lettuce, celtuce, chicory, curly endive, chicory escarole, escarole, cress, salad burnet.

salad green (noun)	endive (noun)
greens suitable for eating uncooked as in salads	variety of endive having leaves with irregular frilled edges
	widely cultivated herb with leaves valued as salad green; either curly serrated leaves or broad flat ones that are usually blanched