mud flat vs parcel of land

mud flat and parcel of land both are nouns.

Word	Noun	Adjective	Verb	Adverb
mud flat	Yes	No	No	No
parcel of land	Yes	No	No	No

As nouns, parcel of land is a hypernym of mud flat; that is, parcel of land is a word with a broader meaning than mud flat:

mud flat: a tract of low muddy land near an estuary; covered at high tide and exposed at low tide
parcel of land: an extended area of land

Other hypernyms of mud flat include parcel, piece of ground, piece of land, tract.

mud flat (noun)	parcel of land (noun)
a tract of low muddy land near an estuary; covered at high tide and exposed at low tide	an extended area of land