alkyl vs methyl group

alkyl and methyl group both are nouns.

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

As nouns, methyl group is a hyponym of alkyl; that is, methyl 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
methyl group: the univalent radical CH3- derived from methane

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

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