cacodyl group vs chemical group

cacodyl group and chemical group both are nouns.

Word	Noun	Adjective	Verb	Adverb
cacodyl group	Yes	No	No	No
chemical group	Yes	No	No	No

As nouns, chemical group is a hypernym of cacodyl group; that is, chemical group is a word with a broader meaning than cacodyl group:

cacodyl group: the univalent group derived from arsine
chemical group: (chemistry) two or more atoms bound together as a single unit and forming part of a molecule

Other hypernyms of cacodyl group include group, radical.

cacodyl group (noun)	chemical group (noun)
the univalent group derived from arsine	(chemistry) two or more atoms bound together as a single unit and forming part of a molecule