sideline vs touchline

sideline and touchline both are nouns.

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

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

sideline (noun)	touchline (noun)
an auxiliary activity	either of the sidelines in soccer or rugby
an auxiliary line of merchandise
a line that marks the side boundary of a playing field

sideline (verb)	touchline (verb)
remove from the center of activity or attention; place into an inferior position