The XC90 is an SUV, can have upto three rows of seats, and it's AWD.
The v70 is a fwd wagon. Not to be confused with the Cross Country (xc-70), which is an AWD wagon, with taller tires and higher ground clearnances, similar to the XC90.
It compares to the v70 in that it's a Volvo, full of safety innovations, and the quality, workmanship, and expected longevity that Volvo's are legendary for.
Other then that it's tough to compare an AWD SUV with a FWD wagon.
I think engine options are similar, curb weight is similar, and the v70 comes in between 5-10k cheaper depending on add on packages.
Probably MUCH cheaper cost of ownership on the wagon, insurance premiums and all.
Why do you ask?
-bear
BTW...check out volvo's website....every question you could have about any of their products is available, including options, prices, specials, and dealerships:
www.volvocars.com