CCD for bar-code scanning
Simply put, CCDs are CCDs and all operate on the same principle. However, they are not all created equal. I would imagine that CCD's used for barcode application only detect luminance information and not colour. Thus they are simpler and cheaper, as the amount of sensing elements are lower.

(Why lower? Well a colour CCD uses 4 subsensors for each pixel: blue, red and 2 green.)

Scanners may include some "cheats" such as having a 1 dimentional CCD and scanning over the target at a high rate of speed. Others may have full 2D sensors.

A nice example of a 2D black and white CCD can be found in optical mice. You can read here about turning a mouse into a simple scanner (more interesting than practical)