mountain laurel vs American laurel

mountain laurel and American laurel both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain laurel	Yes	No	No	No
American laurel	Yes	No	No	No

As nouns, mountain laurel and American laurel are synonyms defined as:

mountain laurel and American laurel: a North American evergreen shrub having glossy leaves and white or rose-colored flowers

Other synonyms of mountain laurel include calico bush, Kalmia latifolia, wood laurel.

mountain laurel (noun)	American laurel (noun)
a North American evergreen shrub having glossy leaves and white or rose-colored flowers	a North American evergreen shrub having glossy leaves and white or rose-colored flowers
Pacific coast tree having aromatic foliage and small umbellate flowers followed by olivelike fruit; yields a hard tough wood