CMOS: Complementary Metal-Oxide-Semiconductor. You may be familiar with it from digital still cameras. This more affordable chip consumes less power and contains electronics that convert the analog information from the pixels to a digital form. This conversion must be performed off-chip in CCD sensors.
SNR: Signal-to-Noise Ratio. The higher the SNR, the cleaner the image; the lower the SNR, the more noise. Smaller pixels, relatively speaking, have a lower SNR than bigger pixels.