abuki That should probably be more differentiated in the docs.
Thanks for the feedback, we will consider if we can improve the docs.
However IMO the documentation is already rather differentiated, looking at SetEmptyAnimation:
"Sets an empty animation for a track, discarding any queued animations, and sets the track entry's mixDuration. An empty animation has no timelines and serves as a placeholder for mixing in or out."
IMO that would be very strange and complicated wording if it meant the same as "clears the track". An animation is an animation, the empty animation is not no animation .
Also AnimationState reads:
"Applies animations over time, queues animations for later playback, mixes (crossfading) between animations, and applies multiple animations on top of each other (layering)."