forest vs greenwood

forest and greenwood both are nouns.

As nouns, greenwood is a hyponym of forest; that is, greenwood is a word with a more specific, narrower meaning than forest:

Other hyponyms of forest include riparian forest, silva, sylva, tree farm.

forest (noun)	greenwood (noun)
the trees and other plants in a large densely wooded area	woodlands in full leaf
land that is covered with trees and shrubs

forest (verb)	greenwood (verb)
establish a forest on previously unforested land