Exact time between two date-times: days, hours, minutes, and totals in each unit.
Pick a start and end date-time. The calculator shows the gap as days, hours, minutes and seconds, plus the total in each single unit (total hours, total minutes, and so on).
Yes. Both inputs include hours and minutes, so the result is precise to the minute, not just whole days. This is what makes it different from a plain date-difference tool.
Yes. If you reverse them the duration is shown with a minus sign, but the magnitude is the same.