white alder vs pepper bush

white alder and pepper bush both are nouns.

Word	Noun	Adjective	Verb	Adverb
white alder	Yes	No	No	No
pepper bush	Yes	No	No	No

As nouns, white alder and pepper bush are synonyms defined as:

white alder and pepper bush: shrub of eastern and southern coastal United States having beautiful racemes of spice-scented white flowers

Other synonyms of white alder include Clethra alnifolia, summer sweet, sweet pepperbush.

white alder (noun)	pepper bush (noun)
tree of western United States	shrub of eastern and southern coastal United States having beautiful racemes of spice-scented white flowers
shrub of eastern and southern coastal United States having beautiful racemes of spice-scented white flowers