If we combine the comments from Hpshps and Rec, we are pretty close.
The file format redbook uses is call CDA. One feature of this format is self-generated clock. That means the clock is regenerated by looking at a limited run of the data stream in real time. If the data stream contains errors, the generated clock will be a little off and causes jitters.
Now if you make a copy, data streams are treated as files, the software can apply a much better error correction scheme to the data and burn a perfect copy of that data stream to CD-R. If high quality disc is used, you will get much lower error rate at playback and therefore much lower jitters.
You can hear improvement only if you use high quality CD-R and playback on relatively mid to low-end players. Most high-end players have large buffer to store data stream. They can apply extensive error corrections to it and regenerate the clock form there.
The file format redbook uses is call CDA. One feature of this format is self-generated clock. That means the clock is regenerated by looking at a limited run of the data stream in real time. If the data stream contains errors, the generated clock will be a little off and causes jitters.
Now if you make a copy, data streams are treated as files, the software can apply a much better error correction scheme to the data and burn a perfect copy of that data stream to CD-R. If high quality disc is used, you will get much lower error rate at playback and therefore much lower jitters.
You can hear improvement only if you use high quality CD-R and playback on relatively mid to low-end players. Most high-end players have large buffer to store data stream. They can apply extensive error corrections to it and regenerate the clock form there.