Where exactly is the oil leak coming from? If it's from the "pumpkin" it's diff oil. It shouldn't be possible for CV grease to leak, except from the CV boot itself. If it's from the CV axles where they bolt onto the diff housing (shown removed from vehicle below) , it could be diff oil, if the axle bolts or seals are malfunctioning.
If the oil has a strong odor, however, it's likely diff oil. It's wise to have it fixed. Let us know what it was.