indigo broom vs horsefly weed

indigo broom and horsefly weed both are nouns.

Word	Noun	Adjective	Verb	Adverb
indigo broom	Yes	No	No	No
horsefly weed	Yes	No	No	No

As nouns, indigo broom and horsefly weed are synonyms defined as:

indigo broom and horsefly weed: much-branched erect herb with bright yellow flowers; distributed from Massachusetts to Florida

Other synonyms of indigo broom include Baptisia tinctoria, rattle weed.

indigo broom (noun)	horsefly weed (noun)
much-branched erect herb with bright yellow flowers; distributed from Massachusetts to Florida	much-branched erect herb with bright yellow flowers; distributed from Massachusetts to Florida