When you see a user's attendance details page, then you see two things: Total time and Total working time

The same is available in export of attendance as well.

Total time is the difference between the last out punch and the first in punch time of the user

Total working/in time is the difference between the sum of all consecutive out punch and and the in punch of the user. It actually gives a better idea of how much time the user was on the desk or in office.