syndactylism vs syndactyly

syndactylism and syndactyly both are nouns.

Word	Noun	Adjective	Verb	Adverb
syndactylism	Yes	No	No	No
syndactyly	Yes	No	No	No

As nouns, syndactylism and syndactyly are synonyms defined as:

syndactylism and syndactyly: birth defect in which there is partial or total webbing connecting two or more fingers or toes

syndactylism (noun)	syndactyly (noun)
birth defect in which there is partial or total webbing connecting two or more fingers or toes	birth defect in which there is partial or total webbing connecting two or more fingers or toes