hairy finger grass vs crabgrass

hairy finger grass and crabgrass both are nouns.

Word	Noun	Adjective	Verb	Adverb
hairy finger grass	Yes	No	No	No
crabgrass	Yes	No	No	No

As nouns, crabgrass is a hypernym of hairy finger grass; that is, crabgrass is a word with a broader meaning than hairy finger grass:

hairy finger grass: a European forage grass grown for hay; a naturalized weed in United States
crabgrass: grasses with creeping stems that root freely; a pest in lawns

Other hypernyms of hairy finger grass include crab grass, finger grass.

hairy finger grass (noun)	crabgrass (noun)
a European forage grass grown for hay; a naturalized weed in United States	grasses with creeping stems that root freely; a pest in lawns