compendious vs summary

compendious is not a noun while summary is a noun.

Word	Noun	Adjective	Verb	Adverb
compendious	No	Yes	No	No
summary	Yes	Yes	No	No

As adjectives, compendious and summary are synonyms defined as:

Other synonyms of compendious include compact, succinct.

compendious (noun)	summary (noun)
	a brief statement that presents the main points in a concise form

compendious (adjective)	summary (adjective)
briefly giving the gist of something	briefly giving the gist of something
	performed speedily and without formality