gridiron vs playing area

gridiron and playing area both are nouns.

Word	Noun	Adjective	Verb	Adverb
gridiron	Yes	No	No	No
playing area	Yes	No	No	No

As nouns, playing area is a hypernym of gridiron; that is, playing area is a word with a broader meaning than gridiron:

Other hypernyms of gridiron include athletic field, field, playing field.

gridiron (noun)	playing area (noun)
a cooking utensil of parallel metal bars; used to grill fish or meat	a piece of land prepared for playing a game
the playing field on which football is played