According to a test comparison of all 4x4's that I have in front of me, the Landcruiser has a 5 star rating overall, including stability (but also taking into account engine and braking performance) whereas of all the XC90 models only the V8 got 5 stars (presumably on account of engine performance). All the other variants were 4 star.
The fuel consumption figures quoted were as follows:
XC90 V8 - 21.1mpg
XC90 D5 - 34.5mpg
XC90 3.2 - 24.4mpg
XC90 2.5T - 25.5mpg
Landcruiser 4.0V6 - 22.3mpg
Landcruiser 3.0D - 31.4mpg