luncheon vs meal

luncheon and meal both are nouns.

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

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

Other hypernyms of luncheon include repast.

luncheon (noun)	meal (noun)
a midday meal	the food served and eaten at one time
	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