Master fader vs master volume

Just wondering what the difference is between these two things on the master bus? There’s the fader just like any other track/bus, but also the “Master output volume” which non of the others have.

I ran the loudness assistant, and noticed it adjusted the blue Master output volume. I never messed with that before and always adjusted the fader.

Can you capture a picture and highlight what you are referring to?

I see what you are referring to now.
In the manual page for the Master bus strip it is referred to as part of the Loudness Analyzer & Normalization tool:

The loudness analyzer is described here:

Enabling that is optional, when present it lets you use the fader as you usually would, meaning you can automate level changes and fades, and then the gain control of the loudness analyzer allows setting an offset for hitting a specific loudness target.

Wow, that explains it then thanks for the links!

I did run the LAN and apply the results, I now need to work out how to undo whatever I did then by the look of it. Hopefully that’s just resetting/shift click that blue Master output volume slider in the middle?

Should be. You can double click and type in 0.0 to get it back to exactly unity.