pursuit vs sideline

pursuit and sideline both are nouns.

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

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

pursuit: a diversion that occupies one's time and thoughts (usually pleasantly)
sideline: an auxiliary activity

Other hyponyms of pursuit include avocation, by-line, hobby, pursuit, spare-time activity.

As nouns, pursuit and sideline are synonyms defined as:

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

pursuit (noun)	sideline (noun)
the act of pursuing in an effort to overtake or capture	an auxiliary activity
a diversion that occupies one's time and thoughts (usually pleasantly)	an auxiliary line of merchandise
an auxiliary activity	a line that marks the side boundary of a playing field
a search for an alternative that meets cognitive criteria

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