[kryptk]

High end mesh network devices have a dedicated high band (5.8ghz) backhaul radio in addition to their usual low-mid 5ghz and 2.4ghz radios used for clients.

The extra radio allows them to blow the pants off any repeater in terms of performance.

They also claim to do some network optimization, for example if you have a device that's constantly streaming Netflix it will be assigned appropriate QoS automatically.