general delivery vs social unit

general delivery and social unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
general delivery	Yes	No	No	No
social unit	Yes	No	No	No

As nouns, social unit is a hypernym of general delivery; that is, social unit is a word with a broader meaning than general delivery:

general delivery: the part of a post office that handles mail for persons who call for it
social unit: an organization regarded as part of a larger social group

Other hypernyms of general delivery include unit.

general delivery (noun)	social unit (noun)
the part of a post office that handles mail for persons who call for it	an organization regarded as part of a larger social group