coin collecting vs aggregation

coin collecting and aggregation both are nouns.

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

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

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

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

coin collecting (noun)	aggregation (noun)
the collection and study of money (and coins in particular)	the act of gathering something together
	several things grouped together or considered as a whole