coin collecting vs collecting

coin collecting and collecting both are nouns.

Word	Noun	Adjective	Verb	Adverb
coin collecting	Yes	No	No	No
collecting	Yes	No	No	No

As nouns, collecting is a hypernym of coin collecting; that is, collecting is a word with a broader meaning than coin collecting:

coin collecting: the collection and study of money (and coins in particular)
collecting: the act of gathering something together

Other hypernyms of coin collecting include aggregation, assembling, collection.

coin collecting (noun)	collecting (noun)
the collection and study of money (and coins in particular)	the act of gathering something together