sum total vs collection

sum total and collection both are nouns.

Word	Noun	Adjective	Verb	Adverb
sum total	Yes	No	No	No
collection	Yes	No	No	No

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

Other hypernyms of sum total include accumulation, aggregation, assemblage.

sum total (noun)	collection (noun)
the final aggregate	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