shell collecting vs collection

shell collecting and collection both are nouns.

Word	Noun	Adjective	Verb	Adverb
shell collecting	Yes	No	No	No
collection	Yes	No	No	No

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

Other hypernyms of shell collecting include aggregation, assembling, collecting, malacology.

shell collecting (noun)	collection (noun)
the collection and study of mollusc shells	the act of gathering something together
	a publication containing a variety of works
	request for a sum of money
	several things grouped together or considered as a whole