CCD stands for "charge-coupled device," while CMOS stands for "complementary metal-oxide semiconductor." The purpose of both is to capture light and convert it into electric signals. This is accomplished through a two-dimensional array of minute solar cells that transform the light from an image into usable signals.
A CCD image sensor transports the charge and converts the analogue values into digital ones. A CMOS sensor accomplishes the same task by using multiple transistors that amplify the charge across traditional wires. Although CCD sensors consume more power, they provide images of better quality. On the other hand, the transistors used in CMOS sensors tend to block the photons from hitting the photodiode, which results in relatively poorer image quality.