curb vs curbstone

curb and curbstone both are nouns.

Word	Noun	Adjective	Verb	Adverb
curb	Yes	No	Yes	No
curbstone	Yes	No	No	No

curb (noun)	curbstone (noun)
the act of restraining power or action or limiting excess	a paving stone forming part of a curb
an edge between a sidewalk and a roadway consisting of a line of curbstones (usually forming part of a gutter)
a horse's bit with an attached chain or strap to check the horse

curb (verb)	curbstone (verb)
place restrictions on
keep to the curb
lessen the intensity of; temper; hold in restraint; hold or keep within limits