siding vs sidetrack

siding and sidetrack both are nouns.

Word	Noun	Adjective	Verb	Adverb
siding	Yes	No	No	No
sidetrack	Yes	No	Yes	No

As nouns, siding and sidetrack are synonyms defined as:

siding and sidetrack: a short stretch of railroad track used to store rolling stock or enable trains on the same line to pass

Other synonyms of siding include railroad siding, turnout.

siding (noun)	sidetrack (noun)
a short stretch of railroad track used to store rolling stock or enable trains on the same line to pass	a short stretch of railroad track used to store rolling stock or enable trains on the same line to pass
material applied to the outside of a building to make it weatherproof

siding (verb)	sidetrack (verb)
	wander from a direct or straight course