Just as an example, the GE 45631 talks a lot about “scenes.” It can be added to your SmartThings account. And you can set up its button presses to control Z wave devices that are in the same room with it. But you can’t use it to change a mode or arm smart home monitor or run a routine or control a Z wave device on the other side of the house or control a zigbee device, because it doesn’t send its button presses to the SmartThings hub.
Search the forums for that model and you will find dozens of discussions about it, because initially people were confused about why it seemed to do some things and not others.
http://products.z-wavealliance.org/products/165
The answer is technical, but specific, and still applies to many Z wave devices. I just can’t tell yet whether it applies to these new ones.
The similar form factor Enerwave SC7 or the remotec eight button device, in contrast, do send their button presses to the hub, and so they can be used for all of the functions I mentioned. But you can’t tell from just looking at the physical device, you have to find out what specific zwave commandsets they use.
More discussion in the following thread: