2003 trailblazer 4x4 front end vibration

I took of the front wheels and found a grumbling noise where the cv joint goes into the front diff. I spun the shaft with the hub disconnected. I was told that it is the cv bearing, but how do I tell if it is that or the diff bearing.

This is the rest of the info for the question. It starts at about 10 mph and does not rise as mph rise and continues to I stop. Also the front left cv axle is harder to turn that the right side.