grain vs wheat berry

grain and wheat berry both are nouns.

Word	Noun	Adjective	Verb	Adverb
grain	Yes	No	Yes	No
wheat berry	Yes	No	No	No

As nouns, wheat berry is a hyponym of grain; that is, wheat berry is a word with a more specific, narrower meaning than grain:

grain: foodstuff prepared from the starchy grains of cereal grasses
wheat berry: grains of common wheat; sometimes cooked whole or cracked as cereal; usually ground into flour

As nouns, wheat berry is a hyponym of grain; that is, wheat berry is a word with a more specific, narrower meaning than grain:

grain: dry seed-like fruit produced by the cereal grasses: e.g. wheat, barley, Indian corn
wheat berry: a grain of wheat

Other hyponyms of grain include amaranth, barleycorn, kernel, rye.

grain (noun)	wheat berry (noun)
the direction, texture, or pattern of fibers found in wood or leather or stone or in a woven fabric	grains of common wheat; sometimes cooked whole or cracked as cereal; usually ground into flour
the physical composition of something (especially with respect to the size and shape of the small constituents of a substance)	a grain of wheat
the smallest possible unit of anything
foodstuff prepared from the starchy grains of cereal grasses
a relatively small granular particle of a substance
dry seed-like fruit produced by the cereal grasses: e.g. wheat, barley, Indian corn
a cereal grass
1/7000 pound; equals a troy grain or 64.799 milligrams
1/60 dram; equals an avoirdupois grain or 64.799 milligrams
a weight unit used for pearls or diamonds: 50 mg or 1/4 carat
the side of leather from which the hair has been removed

grain (verb)	wheat berry (verb)
form into grains
become granular
thoroughly work in
paint (a surface) to make it look like stone or wood