Hi,
It could be that the two different temps. are causing due to the fact:
Package temp sensor (the real important one) which is seated just beneath the top cooling plate of the professor.
Then there are others inside the cpu chip itself, however these are not real core temp sensors, instead they are virtual ones, calculated values from each core load and the package temp. sensor.
Now, even so the the temp sensors from its individual cores are actually quite accurate and usually correspond very well to the real temp. sensor at the top-plate of the professor.
Why You have this big discrepancy I can't understand, but download the free HWmonitor and check all the temps.
http://www.cpuid.com/softwares/hwmonitor.html
Make sure to clear the check-box for any third party s/w during installation.
There are three columns: Value which means the actual readings right now.
Min and max speaks for them self's.
Best regards from Sweden
[Edit] Have HWmonitor on, then start a heavy task such a game or something, after a couple of minutes check the readings from all temp sensors, especially the Max column and compare.