Pressed commercial CDs can sound significantly different from one another,Ans any burnt copies of these will have more error corrections that have to be done. Because of what you see and the laser has to see in the link below
Left moulded/stamped retail CD pits
Middle and right burnt CD-R pits one gold one normal silver
https://www.iasa-web.org/sites/default/files/tc05-fig20.jpg
Cheers George