sweet pepperbush vs white alder

sweet pepperbush and white alder both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweet pepperbush	Yes	No	No	No
white alder	Yes	No	No	No

As nouns, sweet pepperbush and white alder are synonyms defined as:

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

Other synonyms of sweet pepperbush include Clethra alnifolia, pepper bush, summer sweet.

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