leak from differential.

I'm not sure if you're asking if you have a front pinion seal leak or an axle seal leak; two entirely different things. My suggestion would be to take a couple cans of brake parts cleaner and clean off the excess, put the vehicle on a lift, or on jack stands, and run it in gear for a few minutes (in gear at idle should be sufficient if it's a major leak) to find where the fluid comes out. If not a major leak, may need to clean it off then go for a drive for 30 min and re-check.