comparing vs likening

comparing and likening both are nouns.

Word	Noun	Adjective	Verb	Adverb
comparing	Yes	No	No	No
likening	Yes	No	No	No

As nouns, likening is a hyponym of comparing; that is, likening is a word with a more specific, narrower meaning than comparing:

Other hyponyms of comparing include analogy, collation, confrontation, contrast.

comparing (noun)	likening (noun)
the act of examining resemblances	the act of comparing similarities