horse of another/different color, a

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.
See also: color, different, horse, of

horse of another 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 another color.
See also: another, color, horse, of
Farlex Dictionary of Idioms.

(a) horse of another color

 and a horse of a different color
Fig. another matter altogether. I was talking about trees, not bushes. Bushes are a horse of another color. Gambling is not the same as investing in the stock market. It's a horse of a different color.
See also: another, color, horse, of
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

horse of another/different color, a

A different affair altogether. This term was more or less invented by Shakespeare, who in Twelfth Night (2.3) wrote, “My purpose is, indeed, a horse of that colour,” meaning, my aim is indeed something like that. Eventually this was changed to difference rather than likeness, as in Anthony Trollope’s Last Chronicles of Barset (1867): “What did you think of his wife? That’s a horse of another colour altogether.”
See also: another, different, horse, of
The Dictionary of Clichés by Christine Ammer
See also:
  • a horse of another
  • a horse of another color
  • a horse of another colour
  • (you) wanna make something of it?
  • a fast talker
  • (you've) got to get up pretty early in the morning to (do something)
  • a/the feel of (something)
  • (I) wouldn't (do something) if I were you
  • a straw will show which way the wind blows
  • a crack at (someone or something)