The tested Z-Wave devices operate at 868MHz for the UK and Europe, and 908MHz for the USA.
Each Z-wave device is defined by a set of Command Classes, which are broadly equivalent to ZigBee Clusters, and a set of Configuration parameters. Most devices have only a single End Point, which is defined within the Command Class.
In general, the Z-Wave devices operate, and communicate with the hub, in a similar way to the ZigBee devices. The main difference is that, being manufactured by Sigma Designs, the communication between the between the hub processor and the network chip is standardised, and is defined through an API. Although the Z-Wave protocol has been improved over time, unlike the ZigBee protocol, backwards compatibility with the older devices has been retained.