Typically these springs are made in Australia. So they drive on the other side of the rig. They made A B springs because they are assuming that there will be more weight on the rights side with the Battery and the driver and what ever the driver carries behind them. They figured it will level out the Jeep, but here in the US we drive on the other side so the rule of thumb is have the taller spring in the front where the driver is and the taller spring in the rear pass side, but as
@bobthetj03 it could differ based on the Jeep, but really even if you got it wrong it is going to be hardly noticeable and you wont notice it driving it.
I did mine as I suggested above, but I have dual batteries at 50 lbs each so I have 100 lbs more on my passenger side than most Jeeps. So I probably could have gotten away with putting both tall on either side on mine. But like I said as
@bobthetj03 indicated once you get it installed if it is to far off you can swap them side to side.
Honestly I know guys who didn't know anything about the AB and just slapped them in willy nilly and never had any issues.
My opinion is they are barely 1/2 inch different. At worst you will get about a 1/2 inch offset and you won't even notice that without a tape. Most likely your flares are off and will make it look off before you even see what the springs are doing.
Also don't get hung up on how it looks right when you put it on. I mean you will see the lift and get excited as you should, but it may sit one way or the other till they settle down. I mean i would give a couple of months before letting you OCD kick in.
One last thing if it does drive you crazy make sure you are looking on flat ground because with the short wheelbase you will look off on uneven ground regardless.
I hope this helps, and post pics!