demote vs sideline

demote is not a noun while sideline is a noun.

Word	Noun	Adjective	Verb	Adverb
demote	No	No	Yes	No
sideline	Yes	No	Yes	No

As verbs, sideline is a hyponym of demote; that is, sideline is a word with a more specific, narrower meaning than demote:

demote: assign to a lower position; reduce in rank
sideline: remove from the center of activity or attention; place into an inferior position

Other hyponyms of demote include reduce.

demote (noun)	sideline (noun)
	an auxiliary activity
	an auxiliary line of merchandise
	a line that marks the side boundary of a playing field

demote (verb)	sideline (verb)
assign to a lower position; reduce in rank	remove from the center of activity or attention; place into an inferior position