Kentishman.
There is an extremely informative thread, indeed, other threads here about meter accuracy. Do a search of the forum for meters and accuracy. That should highlight the many previous discussions about the subject. The meters are as accurate as they can be with the present technology. Unless we wish to pay 100's of pounds for a meter, that, I am afraid is as good as it gets for now. In the future.....who knows.
NO meter will ever read the same as another unless you are very fortunate. We just have to work with the meters we have and comparing one against another is not recommended. Stick with one meter and it's readings instead. There will then be no discrepancy.
I use one meter all the time and have no problems with any readings, they usually just confirm what I thought my readings might be and TBH I tend not to worry much about slight inaccuracies. They balance out in the end.
All meter's are built to the same EU tolerances.
Ken