ethyl vs alkyl group

ethyl and alkyl group both are nouns.

Word	Noun	Adjective	Verb	Adverb
ethyl	Yes	No	No	No
alkyl group	Yes	No	No	No

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

ethyl: the univalent hydrocarbon radical C2H5 derived from ethane by the removal of one hydrogen atom
alkyl group: any of a series of univalent groups of the general formula CnH2n+1 derived from aliphatic hydrocarbons

Other hypernyms of ethyl include alkyl, alkyl radical.

ethyl (noun)	alkyl group (noun)
the univalent hydrocarbon radical C2H5 derived from ethane by the removal of one hydrogen atom	any of a series of univalent groups of the general formula CnH2n+1 derived from aliphatic hydrocarbons