philately vs stamp collection

philately and stamp collection both are nouns.

Word	Noun	Adjective	Verb	Adverb
philately	Yes	No	No	No
stamp collection	Yes	No	No	No

As nouns, philately and stamp collection are synonyms defined as:

philately and stamp collection: the collection and study of postage stamps

Other synonyms of philately include stamp collecting.

philately (noun)	stamp collection (noun)
the collection and study of postage stamps	the collection and study of postage stamps
	a collection of stamps