Check the link. The MBP 15" is 4.02 pounds. 13" is 3.02 pounds. Also the dimensions are roughly the same

  +-----------+------------------+--------------------+
  | Dimension |     MBP 15"      |      XPS 15"       |
  +-----------+------------------+--------------------+
  | Height    | 0.61"            | 0.45-0.66"         |
  | Width     | 13.75"           | 14.06"             |
  | Depth     | 9.48"            | 9.27"              |
  | Weight    | 4.02 lbs/1.83 kg | 4.50 lbs (2.04 kg) |
  +-----------+------------------+--------------------+

And the battery life is 7 hours for the 84Whr model. http://www.anandtech.com/show/10116/the-dell-xps-15-9550-rev...

In another review it was 8 hours for playing video. Less than MBP at 10 hrs.