greengrocer vs grocer

greengrocer and grocer both are nouns.

Word	Noun	Adjective	Verb	Adverb
greengrocer	Yes	No	No	No
grocer	Yes	No	No	No

As nouns, grocer is a hypernym of greengrocer; that is, grocer is a word with a broader meaning than greengrocer:

greengrocer: a grocer who sells fresh fruits and vegetables
grocer: a retail merchant who sells foodstuffs (and some household supplies)

greengrocer (noun)	grocer (noun)
a grocer who sells fresh fruits and vegetables	a retail merchant who sells foodstuffs (and some household supplies)