horse of a different color

Something completely different or separate, especially in comparison to something else. I've always found math to be easy, but calculus is a horse of a different color.

Common Names:

Name	Pronounced	Usage
Ananth	-	Tamil, Indian, Telugu, Kannada
Sylwester	sil-VES-ter	Polish
Rory	['rɔ:ri]
Iliana	-	Greek, Bulgarian
Abrikosor	[əbri'kɔsɔf]
Roar	-	Norwegian