meal vs snack

meal and snack both are nouns.

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

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

meal (noun)	snack (noun)
the food served and eaten at one time	a light informal meal
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

meal (verb)	snack (verb)
	eat a snack; eat lightly