philately vs aggregation

philately and aggregation both are nouns.

Word	Noun	Adjective	Verb	Adverb
philately	Yes	No	No	No
aggregation	Yes	No	No	No

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

Other hypernyms of philately include assembling, collecting, collection.

philately (noun)	aggregation (noun)
the collection and study of postage stamps	the act of gathering something together
	several things grouped together or considered as a whole