In Scheduler, if you check shift details by clicking on shift you'll find shift details specifically the start and end time of the shift. This is 'Shift' time. However, there are certain cases wherein, the carer and/or client may be slightly different from the 'Shift' time. And this is because they have actually been changed.
To do this, you have to access Advanced edit option when editing a shift.
Note! For Invoicing we always follow Client's Start and End time. For Timesheet, we follow carer.