Sony W800 has a
20.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized CCD sensor . On the other hand, Sony RX1R has a
24.0MP Full frame (35.8 x 23.9 mm ) sized CMOS sensor .
One other difference between these two cameras that is worth mentioning is that Sony RX1R's sensor doesn't have an anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the W800 and RX1R sensor size comparison.
As seen above, Sony RX1R has a 30.5x Larger sensor area than Sony W800. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.