What's the difference between 'manual and 'once' option in macro?

[commriv]

I cant find it anywhere. Im actually making that my bots are going to log out before ss. I made macro with logout if its 10min before ss where I've choosen the 'once' option and then I put it in cavebot as a point to check.

It worked today , but Im curious if it would be better if I would choose a manual option? Is it better ? How it works :S