collation vs assembling

collation and assembling both are nouns.

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

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

Other hypernyms of collation include aggregation, collecting, collection.

collation (noun)	assembling (noun)
careful examination and comparison to note points of disagreement	the act of gathering something together
assembling in proper numerical or logical sequence
a light informal meal