American feverfew vs subshrub

American feverfew and subshrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
American feverfew	Yes	No	No	No
subshrub	Yes	No	No	No

As nouns, subshrub is a hypernym of American feverfew; that is, subshrub is a word with a broader meaning than American feverfew:

American feverfew: stout perennial herb of the eastern United States with whitish flowers; leaves traditionally used by Catawba Indians to treat burns
subshrub: low-growing woody shrub or perennial with woody base

Other hypernyms of American feverfew include suffrutex.

American feverfew (noun)	subshrub (noun)
stout perennial herb of the eastern United States with whitish flowers; leaves traditionally used by Catawba Indians to treat burns	low-growing woody shrub or perennial with woody base