American spelling vs curb

American spelling and curb both are nouns.

Word	Noun	Adjective	Verb	Adverb
American spelling	Yes	No	No	No
curb	Yes	No	Yes	No

American spelling (noun)	curb (noun)
English orthography used in the United States (characterized by 'analyze', 'center', 'usable')	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

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