Topic has been discussed to death a couple of times... General consensus is, yes, CD-Rs do sound different (player specific as well), but most of the differences is introduced during PLAYBACK. The media itself is still identical.
Digital is digital, and remains the same no matter how many times you burn and rip a CD. Most ripping programs will tell you if there are errors during ripping, and CD verification will make sure your burns are spot-on.
You can test this out for yourself... get a 16/44 track, burn it to CD, then rip it and compare against the original in a DAW.
These will degrade the audio, though:
1) Burning from MP3, reripping, reencoding
2) Burning from higher bitrate/sampling rate, reripping
3) Faulty CD-ROM that can't rip properly and/or blemishes on the CD-R surface (read error while ripping - usually software will notify you of this)