Hi
As already mentiioned, the sensors seem to be more accurate if applied 12-24 hours before activating. That's my experience, certainly.
Also, comparing the results of devices, be it a variety of glucometers, Libre or whatever else, there will likely be a difference. There are lots of variables - the meters themselves, even if same make/model, each test strip can produce a different result, a new tub of test strips can produce a different result. It's quite likely to produce a different reading if you were to test the same blood from a finger prick on different test strips/meters etc.
With the Libre, it takes the interstitial fluid a bit longer to change up or down as per the glucose level in the blood, especially when the blood glucose is changing quickly.
There is also an acceptable range for any difference (sorry, can't quote the figures)
So, in view of your results so far, I would say you are getting pretty good readings from the Libre, on the whole. The high and low readings are likely to be a bit more extreme than a glucometer but, again, this is normal and acceptable.
I hope you get to like the Libre system - most become 'addicted'