postal service vs communicating

postal service and communicating both are nouns.

Word	Noun	Adjective	Verb	Adverb
postal service	Yes	No	No	No
communicating	Yes	No	No	No

As nouns, communicating is a hypernym of postal service; that is, communicating is a word with a broader meaning than postal service:

postal service: the system whereby messages are transmitted via the post office
communicating: the activity of communicating; the activity of conveying information

Other hypernyms of postal service include communication.

postal service (noun)	communicating (noun)
the system whereby messages are transmitted via the post office	the activity of communicating; the activity of conveying information