sideline vs kick downstairs

sideline is a noun but kick downstairs is not a noun.

Word	Noun	Adjective	Verb	Adverb
sideline	Yes	No	Yes	No
kick downstairs	No	No	Yes	No

As verbs, kick downstairs is a hypernym of sideline; that is, kick downstairs is a word with a broader meaning than sideline:

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

Other hypernyms of sideline include break, bump, demote, relegate.

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

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