Appy types:

[Irene M Burnett <renieburnett@juno.com>]

Judy, Now that was an intelligent question and observation!!  

Although I believe the Appaloosa WAS a specific breed (There are spotted
horses in European Countries, have been f or centuries),  the App
Registry, in it's early days, registered spotted horses.  It really
didn't matter if they were "original" type, Quarter type, Thoroughbred
type or whatever.  
I have seen Racing Appaloosa, on the track.  Thoroughbred type.
I have had Appy's on Endurance rides kick dirt in my face.  Original or
Arab cross.
I have seen them rein, cut, run barrels and be used for roping. 
Quarterhorse type
I have seen them do dressage, eventing and show jumping.  Warmblood type
There are Appy ponies, Appy miniatures, and Appy mules.
 
My only observation...at one time, Appys gained a bad reputation because
breeders were only interested in color and therefore bred only for that,
forgetting that disposition and conformation are, IMO, a heckof a lot
more important!!!

These observations apply to Pintos and Paints, as well as Palominos. 
When ANY animal is bred for a SPECIFIC trait, ie color, size, speed etc.
etc.  WITHOUT taking into consideration the whole package, you CAN end up
with a mess.  Renie