Olympus TG-870 has a 16.0MP 1/2.3" (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features TruePic VII processor. On the other hand, Fujifilm X30 has a 12.0MP 2/3" (8.8 x 6.6 mm ) sized CMOS X-TRANS II sensor and features EXR Processor II processor.
Below you can see the TG-870 and X30 sensor size comparison.
As seen above, Fujifilm X30 has a 2.1x Larger sensor area than Olympus TG-870. 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.