Nikon P7100 has a 10.0MP 1/1.7" (7.44 x 5.58 mm ) sized CCD sensor and features Expeed C2 processor. On the other hand, Kodak Astro Zoom AZ651 has a 21.0MP 1/2.3" (6.17 x 4.55 mm ) sized CMOS sensor . Kodak Astro Zoom AZ651's sensor provides 11MP more than Nikon P7100's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the P7100 and Astro Zoom AZ651 sensor size comparison.
As seen above, Nikon P7100 has a 1.5x Larger sensor area than Kodak Astro Zoom AZ651. 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.