Leica X-U has a 16.0MP APS-C (23.6 x 15.7 mm ) sized CMOS sensor . On the other hand, Olympus TG-6 has a 12.0MP 1/2.3 (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features TruePic VIII processor.
Below you can see the X-U and TG-6 sensor size comparison.
As seen above, Leica X-U has a 13.2x Larger sensor area than Olympus TG-6. 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.