collection vs assembling

collection and assembling both are nouns.

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

As nouns, collection and assembling are synonyms defined as:

Other synonyms of collection include aggregation, collecting.

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