collection vs philately

collection and philately both are nouns.

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

As nouns, philately is a hyponym of collection; that is, philately is a word with a more specific, narrower meaning than collection:

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