Like someone above said, it's not that Thoroughbreds are different, it's that all horses are different (both in terms of breed, and in terms of individuals).
They can be put into groups, though, to make categorizing a bit easier. Quarter Horses and Appies are generally "Stock" horses, and have relatively similar traits/excel at similar disciplines. Thoroughbreds are a "Sport" type, and are used for different things.
I have ridden tons of Thoroughbreds, and I love them. Congrats on the new riding program!