Hi Peet,
"step started" vs. "action started":
"step started" is sightly earlier than "action started", because a step contains an action. According to the help doc, "step started" is "The first event triggered when a step starts running".
"step completed" vs. "after step ended"
There are two main difference between these two events (according to the help doc):
1. "after step ended" will be triggered regardless if the step was completed successfully or not, while "step completed" is triggered only if the stepcompleted successfully.
2. If the step completed successfully, "step completed" is earlier than "after step ended". "after step ended" is the last event in the events chain.
Hope it helps :-)
Best regards,
Gary