oatmeal vs meal

oatmeal and meal both are nouns.

Word	Noun	Adjective	Verb	Adverb
oatmeal	Yes	No	No	No
meal	Yes	No	No	No

As nouns, meal is a hypernym of oatmeal; that is, meal is a word with a broader meaning than oatmeal:

oatmeal: meal made from rolled or ground oats
meal: coarsely ground foodstuff; especially seeds of various cereal grasses or pulse

oatmeal (noun)	meal (noun)
porridge made of rolled oats	the food served and eaten at one time
meal made from rolled or ground oats	coarsely ground foodstuff; especially seeds of various cereal grasses or pulse
	any of the occasions for eating food that occur by custom or habit at more or less fixed times