Samsung NX300M has a
20.0MP APS-C (23.5 x 15.7 mm ) sized CMOS sensor and features DRIMe IV processor. On the other hand, Sony A330 has a
10.0MP APS-C (23.5 x 15.7 mm ) sized CCD sensor and features Bionz processor.
Samsung NX300M's sensor provides 10MP more than Sony A330'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 NX300M and A330 sensor size comparison.
Sensor Size and Resolution Comparison image of Samsung NX300M and Sony A330 Cameras
Samsung NX300M and Sony A330 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Sony A330 has 98% larger pixel area (36.75µm 2 vs 18.48µm 2 ) compared to Samsung NX300M, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Samsung NX300M
or the
Sony A330 ,
including hyperfocal distance.