meal vs potluck

meal and potluck both are nouns.

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

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

meal: the food served and eaten at one time
potluck: whatever happens to be available especially when offered to an unexpected guest or when brought by guests and shared by all

meal (noun)	potluck (noun)
the food served and eaten at one time	whatever happens to be available especially when offered to an unexpected guest or when brought by guests and shared by all
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