What is the different between locking diff and the did lock transfer

 

I think you mean the difference between a locking center differential (in the transfercase) and locking axle differentials. Described that way, the difference is almost self-evident. Locking the center differential ensures torque is transferred to both front and rear axles. Locking an axle differential ensures torque is transferred to both the driver and passenger side wheels on that axle.

 

My truck has nether which would be better

 

Start with the locking transfer case. It will be more expensive to lock the axles even if you only do one or the other which would be nearly pointless without the locking t-case.

 

If you lock an axle, but the center differential is not locked, all the torque can go to the axle with no traction so the axle locker would be nearly pointless without a center diff lock. But you do have traction control, so that would help some. Still, a center diff lock would be the first thing to do, and then consider axle lockers or limited slips. For rock crawling and lifting wheels you probably want selectable lockers, but for most street and trail driving, limited slip axle differentials are better. They're better because they're working all the time, compared to a selectable locker where you can forget to lock and then lose momentum, and where you have to unlock to steer. They're also better than an automatic locker which often fails to unlock, twists up your axles. Then they either break your axles and break themselves at the same time or they just keep banging unlocked in corners.