Differences depends on the year model (early, facelift, and now the 2018 version).
Most differences are listed above by JWB, other differences are
Fuel tank size (83l versus the dual 83+67l)
Reverse camera
5 seats versus 7 seats.
Rear aircon.
roof rails.
Some of these is optional extra (ie a GX with 7 seats)
Not sure about if you can get the GX with dual tanks optioned? otherwise you could always get aftermarket tank anyway if you need.
Satnav may only be standard on GXLs after 2014, as the early models only have a multifunction display (ie reverse camera/trip computer).
Toyota factory satnav are known for being very slow to update the maps, and you have to pay to update them. The current (newest available) maps are dated 2016.
I bought a GXL because I wanted all the factory features over the GX, but if I had my time again I would buy a GX (or even a late model 120) for the following reasons.
dual zone AC, never used
Rear aircon, takes up valuable space in the cargo area.
side steps, people give these away if you want to retrofit factory ones, or put some aftermarket brush bars/rock sliders.
steering wheel controls, these are useful, but again something you could retrofit, or not worry about.
Cruise control would be a big one for me, again, aftermarket if needed
colour coded side mirrors, the plastic trim is removable and easily painted
7 seats, never used, removed the seats, sat in garage for a couple years, had to sell them when garage space became issue.
wheels, you can get GXL wheels or FJ cruiser, or aftermarket if you want wider.
Reverse cam, easy to upgrade the headunit to one that is capable of displaying camera and satnav. Early GXLs require expensive additional parts for headunit upgrade.
Roof rails, another giveaway item if you want to retrofit, otherwise almost every roof platform is going to be installed direct to roof mounts.
Other models to consider, if you are towing, the SWB 3 door versions have higher tow capacity.
then the altitude models with the euro spec liftgate (tyre underneath, 83l fuel tank only).
Have a good think about what features you require, as a lot of them can be added aftermarket.
Ask/read on the pradopoint forums for more info, also facebook group aussie 4wd prado 150.
