hot cereal vs grits

hot cereal and grits both are nouns.

Word	Noun	Adjective	Verb	Adverb
hot cereal	Yes	No	No	No
grits	Yes	No	No	No

As nouns, grits is a hyponym of hot cereal; that is, grits is a word with a more specific, narrower meaning than hot cereal:

hot cereal: a cereal that is served hot
grits: coarsely ground hulled corn boiled as a breakfast dish in the southern United States

Other hyponyms of hot cereal include cornmeal mush, mush, hominy grits, kasha, frumenty.

hot cereal (noun)	grits (noun)
a cereal that is served hot	coarsely ground hulled corn boiled as a breakfast dish in the southern United States