CCTV Cameras come in a variety of shapes and sizes. At the heart of these devices is an image device, also known as a CCD image sensor. You will see on technical descriptions that it says “¼” CCD or 1/3” CCD”. Without getting into very technical specifics, if all other thing are equal, a 1/3” yields better results than a ¼”, and a ½” is better than a 1/3”. 98% of what is in the market today is ¼” or 1/3”.

Is there a big difference between a ¼ CCD and 1/3 CCD?
Yes, there is a difference. How much depends on your requirements. If you are not dealing with an overly critical situation, the difference may be minimal, but if you are looking for the best image possible, then yes. It could be the difference between being able to identify someone or not. It's just a single aspect of as number of issues we will address here. Each one having a partial effect towards the ultimate resulting image. All combined results in the difference in quality and price.

“Could I tell the difference between the two?”
If you put them side by side, then absolutely. If they weren't, you probably couldn't tell. An analogy would be if I took a photograph of something with a $5.00 disposable camera, and then took a picture with a $10,000.00 Nikon, could I tell the difference. Both, individually, may look okay. It's when you put them side by side that you see the difference.