RonL said:
Disco 1
Less electrics (abs)
full floater axles
easier to work on
100" wheel base
enclosed CV joints
Cheaper to buy.
Basically the Defender/Range Rover classic powertrain
Disco 2
More electrics(trac control, hill dec contol, & abs al the same system)
100" wheel base but more rear overhang
Semi floater axles
rubber booted CV joints
Basically the P38 Range Rover powertrain
This are the basic differences, the Disco 2 is more refined on the inside and has plastic bumper covers front and rear.
Here's my take:
Disco1
Less electrics, but what is there is old and much less sophisticated, and pre-OBDII means it's very hard to diagnose yourself.
Full floater axles: score
Easier to work on, but then you'll be doing more working because everything is just older
Enclosed CV joints: score
Cheaper to buy: but then, more of their useful life is gone, and they're pretty rusty if you're in the rust belt.
Disco2
More electronics, and in most cases if they fail, you're no worse off than if you didn't have them in the first place.
More rear overhang, detriment if you're building a serious rock crawling. Huge bonus if you're actually using the truck for vacationing with a family.
Basically, what it comes down to is what is the goal of the truck. If you're building a dedicated off-roader, the D1 is cheaper to buy, leaving more money for upgrades, it's more compact, simpler, etc.
If you want a truck you can drive 500 miles per day, for a week, while having space for a family and camping equipment. Then the DII is the way to go.
One thing that has surprised and frustrated some people is hub bearing replacement.
D1 = $30 per hub
DII = Can't be replaced, $250-$350 per for new hub.
Yeah, it sucks. But it's just the way things have gone, all cars are like this now. I believe it's also true that the modern 1 piece bearing designs have better seals and last longer, so you'll be replacing them less often.