Both use similar tools and equipment but the goals for each process are quite different.
Mixing is the blending together (or balancing) of the multiple tracks from a recording session into one stereo mix in a way that’s balanced both in frequencies and volume, where everything can be heard clearly in its own space.
Mastering is the final stage your mixed song goes through to get it into an optimal state for release on to your format of choice and is applied only to the final approved stereo mix.
Mastering involves getting the mix louder and to the correct specification for its destination, for example, online streaming, CD or vinyl.
It also involves trying to correct any sonic imbalances that might be present in the mix such as an overly loud low end or a muddy mid-range which often happens when mixes are done in rooms that might not have much in the way of acoustic treatment and on monitors that don’t represent the full frequency range and therefore influence your mixing decisions in a negative way.
Lastly, mastering can add the final polish or sheen to your mix to help it sound its absolute best and to compete with other commercial releases. Mastering can bring clarity to muddy mixes, create more separation between instruments and add width and, of course, loudness.
Check out the video where I explain the differences between the two and why you should get all your releases mastered if you want them to sound awesome online.
Enter your email address to join my mailing list and get this free bonus