commons vs piece of ground

commons and piece of ground both are nouns.

Word	Noun	Adjective	Verb	Adverb
commons	Yes	No	No	No
piece of ground	Yes	No	No	No

As nouns, piece of ground is a hypernym of commons; that is, piece of ground is a word with a broader meaning than commons:

Other hypernyms of commons include parcel, parcel of land, piece of land, tract.

commons (noun)	piece of ground (noun)
a class composed of persons lacking clerical or noble rank	an extended area of land
a piece of open land for recreational use in an urban area
a pasture subject to common use