alkane vs C2H6

alkane and C2H6 both are nouns.

Word	Noun	Adjective	Verb	Adverb
alkane	Yes	No	No	No
C2H6	Yes	No	No	No

As nouns, C2H6 is a hyponym of alkane; that is, C2H6 is a word with a more specific, narrower meaning than alkane:

alkane: a series of non-aromatic saturated hydrocarbons with the general formula CnH(2n+2)
C2H6: a colorless odorless alkane gas used as fuel

Other hyponyms of alkane include butane, amine, aminoalkane, ethane, heptane, hexane, methane.

alkane (noun)	C2H6 (noun)
a series of non-aromatic saturated hydrocarbons with the general formula CnH(2n+2)	a colorless odorless alkane gas used as fuel