Fujifilm XP90 has a 16.0MP 1/2.3" (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Panasonic G1 has a 12.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor .
Below you can see the XP90 and G1 sensor size comparison.
As seen above, Panasonic G1 has a 8.0x Larger sensor area than Fujifilm XP90. 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.