1. If ClientMatch is enabled, Band Steering is not used
2. If you are using a 802.11nac AP, band steering is not used
3. ClientMatch is enabled by default, so it is rare that band steering is used. You would have to turn client match off and be using and 802.11n or older AP.
4. Band steering happens on client association. Client Match happens after association, after measuring that the 5ghz signal strength is strong enough, first.
5. Client Match is better because it ensures that the 5ghz signal strength would be a certain signal strength before it moves a device.