White balance data in your raw file is not a simple, temperature or color setting. The stored data needs to be interpreted. Different companies do the interpretations a little different from each other.
That said, the difference in your example seems a bit larger than I would expect.
Thanks. The shots look OK, and I normally tweak WB a bit anyway, so I guess in the end it doesn't matter much.
All my cameras show different readings in LR than the in-camera setting. My Canon 5D MKII using in-camera Daylight 5200 WB setting with high-noon sunlight in cloud free sky (5500-6000):
LR 'As Shot' WB 4850 +1
LR 'Daylight' WB 5500 +10
ColorChecker Passport WB calibration 5100 +10
As ManiacJoe mentioned LR takes the camera's RGGB WB reading and then calculates the actual As Shot WB. This can vary from one camera serial number to another of the same model. Lenses can slightly shift the WB due to use of rare earth lens elements or if a UV or Skylight filter is used. You an purchase a white balance card or ColorChecker Passport and check the actual WB settings needed for specific lighting conditions.
Interesting, thanks. I just got one of those WhiBal cards and it seems to be doing the trick so far =)