More. The Appalachian orogeny was one of a number of mountain building events that happened around this time and affecting different parts of the Appalachians. There was the Caledonian, Acadian, Ouachita, Hercynian and Alleghenian events, all of which built a massive mountain range along the east coast. What’s left today are the eroded remnants of this huge range.
Geologically, there are several provinces. Furthest to the west and extending from New York to Alabama is the Appalachian Basin. It’s what geologists call a “foreland basin” - a low lying area that sits in front of a mountain range where the eroded sediments are deposited. These sedimentary layers are mainly flat lying in the Appalachian Plateau and complexly thrust faulted and folded in the Valley and Ridge province. Thrust faults are faults that form when layers of rock are broken and shoved on top of one another when they’re pushed together by tectonic forces.
The Blue Ridge, Piedmont, and Adirondack mountains form the crystalline core of the Appalachians. Unlike the sedimentary rocks in the Appalachian Basin, they are crystalline. Think of rocks that crystallized from magma or that were formed through recrystallization during deep burial and heating. The crystalline rocks of the Blue Ridge mountains are riding on a huge system of thrust faults which are shoved eastward over the Appalachian basin. This means if you could somehow get down below the granite and such, you’ll find more sedimentary rock like you find in the Appalachian Basin.
Here’s a map of the different provinces.