This is a format for presenting fonts in PDF files that was initially conceived to store symbols in the Japanese and Chinese languages because it had a 16-bit structure and allowed for more precise adjustment. CID expands the the potential for PostScript by supporting languages that do not have a left-to-right orientation, and by supporting even a vertical mode of orientation.
This is a format for compact font storage in the OpenType system, allowing for the rasterization of text information. It differs from TrueType in its abilities to describe font symbols and with its font structure variation algorithm, depending on the change in size. CFF allows for increased screen clarity with high resolution, but this is not due to the font, but its rasterization.