Yes, zwave is in the much less congested 900mhz range. It is a fair bit more reliable as it doesn’t compete with:

- WiFi

- Bluetooth

- microwave ovens

Additionally, it’s a bit more strict with certification so you can easily use multiple vendors for zwave whereas with zigbee it’s often a terrible experience since vendors implement things differently in ways that are not as interoperable. In fact, for a device to be certified by the zwave alliance, it must pass strict conformance testing to ensure backwards compatibility and interoperability.