allomorph vs morpheme

allomorph and morpheme both are nouns.

Word	Noun	Adjective	Verb	Adverb
allomorph	Yes	No	No	No
morpheme	Yes	No	No	No

As nouns, morpheme is a hypernym of allomorph; that is, morpheme is a word with a broader meaning than allomorph:

allomorph: a variant phonological representation of a morpheme
morpheme: minimal meaningful language unit; it cannot be divided into smaller meaningful units

allomorph (noun)	morpheme (noun)
a variant phonological representation of a morpheme	minimal meaningful language unit; it cannot be divided into smaller meaningful units
any of several different crystalline forms of the same chemical compound