I know you have probably done this before, but since you asked the question I'm gonna give you the full quick rundown about using a jack and jack stands. If you already know, maybe it'll help someone else who doesn't.
Not only can you lift the Jeep from the diff/axle, but that's where you should place the jack. It would be very unsafe to lift from the frame on one side, place jack stands on that side, then jack up the other side to place jack stands.
Obviously the front diff is offset, so jacking the axle up from it makes the axle tuck on the drivers side and droop on the passenger side a little. It's perfectly fine to use the front diff, but you can also put the jack on the axle tube just to the side of the front diff. It's a static situation, so the forces are so small that you won't hurt anything on the Jeep. But the biggest thing to keep in mind is don't hurt yourself. A Jeep is replaceable/fixable, but it's a lot harder to fix you once a couple thousand pounds falls on you.
Another general rule of thumb about woking on Jeeps - do not rely on the jack to support the weight of the vehicle for extended periods of time. Always use jack stands.