It's possible that I'm wrong making that statement, so let me preface my explanation with the qualifier that I only spent a short day playing with it!
The LabRadar is capable of measurements in intervals all the way to target. In other words, it reads fps at various ranges, so you can know your bullet speed at muzzle, 50 yards, 100 yards, etc. I suspect that's a fairly nice feature for some, but I do not need it, and do not see that the Xero does it. Again, I could be wrong and am happy to be corrected.
It certainly does all that I need it to!

Thanks CMJ, you type faster, and are better with words!