sideline vs by-line

sideline and by-line both are nouns.

Word	Noun	Adjective	Verb	Adverb
sideline	Yes	No	Yes	No
by-line	Yes	No	No	No

As nouns, sideline and by-line are synonyms defined as:

Other synonyms of sideline include avocation, hobby, pursuit, spare-time activity.

sideline (noun)	by-line (noun)
an auxiliary activity	an auxiliary activity
an auxiliary line of merchandise	a line giving the name of the writer of a story or article
a line that marks the side boundary of a playing field

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