Olympus 7040 has a
14.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor and features TruePic III processor. On the other hand, Nikon P7000 has a
10.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized CCD sensor and features Expeed C2 processor.
Below you can see the 7040 and P7000 sensor size comparison.
As seen above, Nikon P7000 has a 1.5x Larger sensor area than Olympus 7040. 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.