First Q: CCD and CMOS in the end mean? 
CCD and CMOS is actually the feeling of the two components of constant, in principle there is no essential difference - is the use of silicon photodiodes for optical and electrical conversion. The main difference is that manufacturing, CCD is integrated in the semi- lead single crystal materials, but CMOS is integrated in the metal-oxide semiconductor, known materials.

Second question: CCD and CMOS Why the price difference so big? 
The advantages of CCD image quality is good, but complex process, this technology is only held by Sony, Panasonic and a few other manufacturers, resulting in high costs.

Third Question: What kind of car actually use it? 
CMOS chip CCD image quality less than that number of poor color reproduction, but because of its low cost, low power consumption and other advantages for the increased demand, while also promoting the technology improved and updated, now is the gap between CMOS and CCD a little narrow, high-end products such as Canon has started to use CMOS chips. So your friends car bold chip CMOS camera with it, like the common OV7950, MT706 and other properties are quite stable, it can achieve the desired effect of reversing aid, and affordable!