Active time = The time spent actively doing something to prepare the recipe (i.e., mixing, chopping, kneading, etc.) Does not include the time spent in the oven, or rising, or marinading, etc.
Total time = Start-to-finish time required for the recipe
Example:
In a bread recipe, it might be 20 minutes of "active time", but 4 hours of "Total Time", because the bread needs to rise, and bake in the oven.