Compares dates in a column to another column of dates, or to a dynamically generated Today value
This step will tell you how far two dates/times are from each other. One of them can be a Today that is calculated fresh each time, so that it is always as accurate as possible.
The Compare dates step creates a new column that shows the measurement of time between the two dates. You can select that unit - from seconds to years.
Really hard, and not fun to think about.
If your data has a timezone, you can indicate that in the step. In that case, Today will use the same time zone. If your data does not have one, you can set a timezone to be used for both your date and the Today date.
Good luck (because you may need it).