methyl radical vs alkyl group

methyl radical and alkyl group both are nouns.

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

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

methyl radical: the univalent radical CH3- derived from methane
alkyl group: any of a series of univalent groups of the general formula CnH2n+1 derived from aliphatic hydrocarbons

Other hypernyms of methyl radical include alkyl, alkyl radical.

methyl radical (noun)	alkyl group (noun)
the univalent radical CH3- derived from methane	any of a series of univalent groups of the general formula CnH2n+1 derived from aliphatic hydrocarbons