comprehend vs digest

comprehend is not a noun while digest is a noun.

Word	Noun	Adjective	Verb	Adverb
comprehend	No	No	Yes	No
digest	Yes	No	Yes	No

As verbs, digest is a hyponym of comprehend; that is, digest is a word with a more specific, narrower meaning than comprehend:

Other hyponyms of comprehend include figure, catch on, cotton on, get it, get onto, get wise, latch on, tumble, twig, intuit.

comprehend (noun)	digest (noun)
	something that is compiled (as into a single book or file)
	a periodical that summarizes the news

comprehend (verb)	digest (verb)
get the meaning of something	make more concise
to become aware of through the senses	systematize, as by classifying and summarizing
include in scope; include as part of something broader; have as one's sphere or territory	become assimilated into the body
	soften or disintegrate by means of chemical action, heat, or moisture
	soften or disintegrate, as by undergoing exposure to heat or moisture
	arrange and integrate in the mind
	put up with something or somebody unpleasant
	convert food into absorbable substances