Quantum Computing, page-60

Zog as for the two different approaches, the way I see it is that one technology uses a control system that uses transistors and wiring in a CMOS technology similar to what they use today, the other method they mention doesn't use Transistors and associated wiring, but uses microwaves to make use of magnetically controlling the spins and readouts which removes the need for transistors or wires ansd some heat, it is a new and novel approach, but they are going ahead with both, the former by the UNSW and the latter by SQC is what I read.
But a heat budget still comes into play using the latter as Quantum Computing likes a stable heat environment as heat changes can lead to errors so they say.