grainfield vs cornfield

grainfield and cornfield both are nouns.

Word	Noun	Adjective	Verb	Adverb
grainfield	Yes	No	No	No
cornfield	Yes	No	No	No

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

Other hyponyms of grainfield include corn field, wheat field, wheatfield.

grainfield (noun)	cornfield (noun)
a field where grain is grown	a field planted with corn