no difference whatsoever
it was just badging like they did on the cavalier, ie cavalier 120 when it was 118bhp
the z22se engine pumps out around 145 bhp, Engine torque 149.7 lbs/ft
the Vectra B Saloon 2.2sri was prob the best 2.2 I come across, the Astra G just feels very unrefined and not as well balanced