ethyl group vs alkyl radical

ethyl group and alkyl radical both are nouns.

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

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

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

Other hypernyms of ethyl group include alkyl, alkyl group.

ethyl group (noun)	alkyl radical (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