groundsel bush vs shrub

groundsel bush and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
groundsel bush	Yes	No	No	No
shrub	Yes	No	No	No

As nouns, shrub is a hypernym of groundsel bush; that is, shrub is a word with a broader meaning than groundsel bush:

groundsel bush: a shrub of salt marshes of eastern and south central North America and West Indies; fruit is surrounded with white plumelike hairy tufts
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of groundsel bush include bush.

groundsel bush (noun)	shrub (noun)
a shrub of salt marshes of eastern and south central North America and West Indies; fruit is surrounded with white plumelike hairy tufts	a low woody perennial plant usually having several major stems