Truclient transactions, what's the difference between "step completed" and "after step ended"?

Hi,

I'm trying to get a better understanding of the definitions of Truclient transaction definitions. There are  a few of which I wonder what the difference is between them, like:

"step started" vs. "action started"

and

"step completed" vs. "after step ended"

If someone can explain the differences to me, that would be great!

Regards,

Peet