mountain laurel vs kalmia

mountain laurel and kalmia both are nouns.

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

As nouns, kalmia is a hypernym of mountain laurel; that is, kalmia is a word with a broader meaning than mountain laurel:

mountain laurel: a North American evergreen shrub having glossy leaves and white or rose-colored flowers
kalmia: any plant of the genus Kalmia

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