There is no such thing as a "Pitbull Whippet"!
It seems you might be mixing up two different breeds:
* Pit Bull: A general term for breeds like the American Staffordshire Terrier, American Pit Bull Terrier, and Staffordshire Bull Terrier—muscular, strong-jawed, generally friendly.
* Whippet: A sighthound with a sleek, slender body, long legs, and incredible speed.
While both are athletic, they differ greatly in appearance and temperament. Let me know if you want a description of a specific breed.