stamp collection vs assembling

stamp collection and assembling both are nouns.

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

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

Other hypernyms of stamp collection include aggregation, collecting, collection.

stamp collection (noun)	assembling (noun)
the collection and study of postage stamps	the act of gathering something together
a collection of stamps