Your CD Player, however good, is working in pretty much realtime. This means that any information taken from the disc by the CD transport has to be processed by the CDP's DAC immediately. As a result the info is taken off quickly and some stuff can be missed. CD players are very good at "filling" these data gaps but they are, to an extent, guessing what should be there through interpolation.
On the other hand music ripped from a CD to an electronic, lossless file, format is not under any time pressure. It can go as fast, or slow, as it needs to so that it extracts all data. The result is so called "bit perfect" data.
Whether or not it sounds any "better" however is in the ears of the listener. I happen to think it does, but many prefer the CD sound in the same way that many prefer vinyl to CD's.