chicory vs salad green

chicory and salad green both are nouns.

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

As nouns, salad green is a hypernym of chicory; that is, salad green is a word with a broader meaning than chicory:

Other hypernyms of chicory include salad greens.

chicory (noun)	salad green (noun)
crisp spiky leaves with somewhat bitter taste	greens suitable for eating uncooked as in salads
root of the chicory plant roasted and ground to substitute for or adulterate coffee
perennial Old World herb having rayed flower heads with blue florets cultivated for its root and its heads of crisp edible leaves used in salads
the dried root of the chicory plant: used as a coffee substitute