aniMate2: I've found no differences between 'sub track' and 'level'

iSeeThis

I've used it for a while. I guess my understanding is very low. But I've tried everything and found that the use of sub track and level is identical. Just that you can name a sub track for easy label. I tend to use it for each individual change (so it may pile up big after I translate, scale, and rotate a lot). But they show clearly what they are for.

For level, it's buried under Base and you have no way to know what you've done with a level. So the question, do I miss some valuable things around here? I never understand why bother put it there. Quite useless in my eyes but there must be something I don't know. Please enlighten me!