Exactly, plus the 15" rMBP has a significantly larger battery than the 14" Razer Blade (95Wh vs 70Wh).
A 37% drop in battery capacity for a 8% smaller chassis seems like a poor tradeoff, especially considering that the Razer appears to have a larger bezel so the screen size/body size ratio isn't as good as well.
It will use less power because of Optimus and the fact it does not have to push a Retina screen. The weight is signifigantly less than the 15" rMBP as well.