Fujifilm XQ1 has a 12.0MP 2/3" (8.8 x 6.6 mm ) sized CMOS X-TRANS II sensor . On the other hand, Olympus E-PL8 has a 16.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor and features TruePic VII processor.
Below you can see the XQ1 and E-PL8 sensor size comparison.
As seen above, Olympus E-PL8 has a 3.9x Larger sensor area than Fujifilm XQ1. 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.