compendium vs collection

compendium and collection both are nouns.

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

As nouns, compendium and collection are synonyms defined as:

compendium (noun)	collection (noun)
a concise but comprehensive summary of a larger work	the act of gathering something together
a publication containing a variety of works	a publication containing a variety of works
	request for a sum of money
	several things grouped together or considered as a whole