Does Orvis teach a different casting style than the rest.
No, they do not. The casting style that is taught during any casting lesson is depend on the skill and knowledge of the individual instructor leading that class. Obviously, some instructors are better at certain styles than others, regardless of the location offering the lesson.
If you are interested in a specific casting style or technique, then I recommend discussing what you want with the instructor before booking the lesson. You might even talk to several and then book the lesson with whichever instructor you feel best meets your needs.