Here at StorefrontHardware.com, we carry all three types of Exit Devices.
Some people may refer to Exit Devices as "Crash Bars" or "Panic Hardware." It all means the same thing. Here is a little "go-to" to help you know what's what:
Rim Exit Device: is mounted on the surface of the door and locks to the frame or to a mullion.
Concealed Vertical Rod Device (CVR): is mounted on the inside of the door and is commonly used on doors where an architect has been very specific about aesthetics. The locks are on the tops and bottoms of the rods that run vertically inside the door.
Surface Vertical Rod Device (SVR): is very similar to the CVR in which the locks are on the top and bottom of the device locking into the header and the footer. Unlike the CVR, the SVR mounts on the exterior of the door.