Hi Zd,
I think you'll find that there are very few external optical drives available that have eSATA interfaces, with the vast majority of them being USB.
Although if you were to particularly want to go eSATA for some reason you could purchase an external enclosure providing that interface, and install into it a drive designed for internal use, almost all internal optical drives having SATA interfaces.
As far as possible differences are concerned, as long as you rip with software that assures bit perfect accuracy I can't envision any reason that the type of interface would make any difference during the ripping process.
During the playback process, especially if you are using a USB DAC, I suppose it is possible that the presence of an external optical drive and its power supply could affect noise conditions, either directly or as a result of differences in the processing that goes on within the computer to support the particular interface. That might in turn ultimately affect jitter at the point of D/A conversion, and/or affect downstream analog circuitry. And if so there might be differences that would correlate with the type of interface. But I'd imagine that any such effects would be both subtle and unpredictable.
The one suggestion I would make if you would be playing back via a USB DAC is that it would seem to be good practice to not have any other USB device connected to a USB port that is paired with the port to which the USB DAC is connected. And also perhaps to try connecting the USB DAC to various ports on the computer and comparing sonics, it being conceivable that they differ somewhat in terms of noise and other waveform characteristics.
BTW, I enjoy reading your many helpful posts in other threads, which are obviously based on a wealth of experience.
Best regards,
-- Al
