ethane vs alkane series

ethane and alkane series both are nouns.

Word	Noun	Adjective	Verb	Adverb
ethane	Yes	No	No	No
alkane series	Yes	No	No	No

As nouns, alkane series is a hypernym of ethane; that is, alkane series is a word with a broader meaning than ethane:

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

Other hypernyms of ethane include hydrocarbon, alkane, methane series, paraffin, paraffin series.

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