If a CD is perfect, there should be no difference in sound between it and a file ripped from it (preferably using EAC). But many CDs have minor (easily recoverable) flaws. Some have worse flaws. If you are playing a CD, there is only a limited amount it can fix in real time, When you rip a file from it, you can take a lot longer to ensure the errors are fixed.
CD transport vs.streaming
Many have stated on this forum that the SQ from their CDs is superior to the sound from streaming sources. Others have said the opposite. Weirdly, in side by side identical tracks the sound from my Cyrus CDt sounds identical to my Cambridge CXN v2 streamer. I wonder if anyone else has this experience.