alkyl vs ethyl group

alkyl and ethyl group both are nouns.

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

As nouns, ethyl group is a hyponym of alkyl; that is, ethyl group is a word with a more specific, narrower meaning than alkyl:

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

Other hyponyms of alkyl include ethyl, ethyl radical, methyl, methyl group, methyl radical.

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