n. phr. , informal Something altogether separate and different. Anyone can be broke, but to steal is a horse of a different color. Do you mean that the boy with that pretty girl is her brother? I thought he was her boyfriend. Well, that's a horse of another color.
HORSE OF A DIFFERENT COLOR
Meaning of HORSE OF A DIFFERENT COLOR in English
American idioms English vocabulary. Английский словарь американских идиом. 2012