Both spellings are correct with exactly the same meaning – a color between white and black. Please note that grey is much more common in British English and gray in American English. The difference in usage between these languages is so strong, that it even applies to scientific names of species, such as grey/gray whale (with the exception of the dog breed name greyhound, which is spelled the same way both in BE and AE. However this breed’s name doesn’t originate in colour so it’s a different story).

Definition of gray/grey:
noun, colour between black and white
I love this grey jumper, it matches my new trousers really well!
I love this gray sweater, it matches my new pants really well!

Correct spelling


Correct spelling, this version is more common in American English.

Correct spelling


Correct spelling, this version is common in all the other main varieties of English (including Britain).