Short answer - yes it's different.
I don't know what you mean by "more stable in its instantaneous value". The CGM return seems to lag blood glucose by about 15-20 minutes. Glucose gets into the bloodstream fairly quickly but then takes longer to get to interstitial fluids.
My experience with CGM is that it showed patterns well (when the sensors worked) but wasn't reliable at individual point measurements - it usually read one or two mmol/l off from the fingerprick, even allowing for lag. The best I got was consistent error/deviation. Where the CGM scored for me was showing what happened when I wouldn't normally be testing blood - when asleep, for example. Having got that info I don't need to repeat the experiment until/unless something changes.
From that, it's obvious that my experience shows that the two systems do not always correlate well. The CGM shows patterns and flows: the fingerprick gives you a more accurate (hopefully?) BG snapshot.
As I'm a diet only T2 predominantly interested in my blood glucose values, with no current hypo/hyper issues, I pay more attention to post-eating fingerprick values and haven't used a CGM for 18 months or so, maybe longer. I don't actually need a CGM at all, and if offered them via the NHS wouldn't take it up.
I think there are others who would benefit more from a CGM, and for example I would think there is value to any T2 newly diagnosed using one for a while for the "ups and downs" information.
I have no idea how the tech side of the sensor works. The microfilament goes through the skin but shouldn't draw blood. Of the three periods of use, one failed after a few days and one never worked at all. Both were replaced by Abbot, but I don't know why they failed.