As a noun, grill refers to (1) a cooking surface using parallel metal bars, (2) a device that cooks with a grill, or (3) a restaurant offering grilled food. As a verb, it means (1) to grill, or (2) to question relentlessly. Grille, which is only a noun, usually refers to a grating used as a screen or barrier on a window or on the front of an automobile.
Grille is often used instead of grill in restaurant names—e.g., Salt Creek Grille, O’Connell’s Irish Pub & Grille, Arooga’s Grille & Sports Bar. There’s no good reason for this. It’s just something some restaurateurs do.
To get all up in [one's] grill is to be extremely annoying, especially through nagging or by covering an opponent closely while playing a sport. Also, in American slang, a grill is a plate molded to the teeth, usually decorated with diamonds or gold. Grill is the conventional spelling for both of these uses even though these senses of the word presumably derive from grille.
The 200 S has a black chrome grille and 18-inch wheels with black accents. [Automobile Magazine]
Police said the thieves climbed a security grille and broke through a second-storey window. [Stonnington Leader]
Maryland lawmakers are planning to grill utility company representatives next week about why so many customers were left in the dark following last week’s snowstorm … [Washington Post]
It may be winter, but don’t try telling that to the grill — or the people who use them. [Delta Optimist]
Here Simms pulled off his gold grill, revealing plain white teeth. [Baltimore City Paper]
Brown hates it when people get all up in his grill, and no one has shown more skill at sticking his nose where it doesn’t belong than Brown himself. [Harvard Crimson]