similarity vs analog

similarity and analog both are nouns.

Word	Noun	Adjective	Verb	Adverb
similarity	Yes	No	No	No
analog	Yes	Yes	No	No

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

similarity (noun)	analog (noun)
the quality of being similar	something having the property of being analogous to something else
a Gestalt principle of organization holding that (other things being equal) parts of a stimulus field that are similar to each other tend to be perceived as belonging together as a unit

similarity (adjective)	analog (adjective)
	of a circuit or device having an output that is proportional to the input