How is a range-extender different to a plug in hybrid? And which is better?

Leapmotor's C10 Hybrid EV is the only REx on sale in the UK - but more are coming
Both PHEV and REx drivetrains combine combustion engines and electric motors, but there are crucial differencesA range-extender (known as a REx or REEV) is pleasingly simple: it's an electric vehicle with a smaller battery that can be topped up by a petrol engine when the state of charge drops.
Traditionally, a REx is a type of series hybrid, which means the electric motor turns the road wheels and t