Nikon D80 has a 10.0MP APS-C (23.6 x 15.8 mm ) sized CCD sensor . On the other hand, Leica Digilux 3 has a 7.0MP Four Thirds (17.3 x 13 mm ) sized CMOS sensor .
Below you can see the D80 and Digilux 3 sensor size comparison.
As seen above, Nikon D80 has a 1.7x Larger sensor area than Leica Digilux 3. 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.