They both read from the digital thermal sensor, just they're not agreeing on what your tjunction max temperature is.
The digital thermal sensor measures the distance from tjunction max, so if they use a different value of tjunction max, the temperatures given will be different.
I've heard a good rule of thumb is to stay above 20C from tjunction max. So if tjunction max is 100C, try not to stay above 80C.
Course you didn't say what CPU you have.