Quick 4WD question

[93'Jag90'325ix98'QX4]

We have the 98 qx4 and it has the seperate actual shifter for High, N, and Low as well as the normal turn knob for 2WD, Auto, and Lock.

Why did some qx4's not have the seperate real shifter and instead have Low as part of the turn knob too?

What purpose does Lock 4WD vs. shifting the real lever into High have in common? Can I put it in High and have the knob on 2WD mode. It's much more unique than the basic shifter in all my past Jeeps that had 2WD, PT, FT, N, & Low. Just wanna make sure I know the ins and outs of the qx4's 4WD!