There's normally a 10% difference which is acceptable.
Did you use a screw-in type of tester? From the picture it looks like a push-fit type which isn't so effective. I used to warm up the engine before taking readings and keep the throttle open.
If there's a wide discrepancy in readings,then squirt some light oil into the plug hole. If compression improves,then it indicates a piston problem. If no difference,then it could be a valve problem. The Haynes manual quotes 8-12 bar with 3 bar maximum difference between cylinders.