It is hard to say, because it depends on the audio codec. Frankly speaking, they are not much different if they are from the same video, unless you have professional speaker or earphone and have extraordinary sense of hearing.
If you still insist on the audio quality, you can download it into WAV format, since WAV will preserve more details than MP3. For more detailed steps, you can refer to this tutorial: How to Download Audio from Website?. Hope is a help.
