The words grill, grille sound the same but have different meanings and spellings. Why do grill, grille sound the same even though they are completely different words?
The answer is simple: grill, grille are homophones of the English language.
Variant of grille.
A series of marks grilled or embossed on a surface.
Food cooked by broiling or grilling.
An opening covered with a grating.
A grating of metal, wood, or another material used as a screen, divider, barrier, or decorative element, as in a window or on the front end of an automotive vehicle.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.