alikeness vs similar

alikeness is a noun but similar is not a noun.

Word	Noun	Adjective	Verb	Adverb
alikeness	Yes	No	No	No
similar	No	Yes	No	No

alikeness (noun)	similar (noun)
similarity in appearance or character or nature between persons or things

alikeness (adjective)	similar (adjective)
	marked by correspondence or resemblance
	resembling or similar; having the same or some of the same characteristics; often used in combination
	having the same or similar characteristics
	capable of replacing or changing places with something else; permitting mutual substitution without loss of function or suitability
	(of words) expressing closely related meanings