LRP AI Pro brushless has a limit of "over" 8.5T, meaning it can run motors down to 9.5T
XBR has a limit of 8.5T meaning the lowest it can run is 8.5T.
Apart from that, XBR has the usual setting options (drag brake, etc) while the AI brushless series figures everything out for you, which can be good or bad depending on what you like.
Lastly, the XBR is smaller than the AI series ESCs, although it's still very big.