Just to be sure we’re all talking about the same thing, these are the Hortsmann RoomThermostat and its receiver, right? Also sold under the Secure brand name.
If so, there’s an existing thread in the forum that discusses those two products and the fact that the switch needs to be reset if you want to use it with smartthings. So I suggest starting with that. If nothing else you should be able to talk to some other community members who are using it. (The topic title is a clickable link)
As for the suffix, It is quite common for device manufacturers who offer the same device in multiple RF protocols do use the suffix to indicate which protocol module is installed in the device. In this case, – ZW just stands for Z wave.
If you meant the letters on the device itself, when all else fails, consult the manual. 
