curtail vs curb

curtail is not a noun while curb is a noun.

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

As verbs, curtail and curb are synonyms defined as:

Other synonyms of curtail include cut back, restrict.

curtail (noun)	curb (noun)
	the act of restraining power or action or limiting excess
	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

curtail (verb)	curb (verb)
place restrictions on	place restrictions on
terminate or abbreviate before its intended or proper end or its full extent	keep to the curb
	lessen the intensity of; temper; hold in restraint; hold or keep within limits