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Script time is the amount of time the script has been running since it first started, was most recently reset, or one of the reset functions was called. It is unaffected by time dilation.
Script time is the amount of real-world time that the script has been in a running state. It is unaffected by time dilation, but it does not count time while the script is suspended, the user is offline (when in an attachment), the object is in inventory rather than rezzed, etc.