Decimal time is usually used for payroll as it is a lot easier to use for the rate calculations and wages calculations.
Decimal time is calculated with decimals after the hour meaning the minutes are converted to a decimal value meaning 30 minutes to decimal time will be 0.5.
Normal time is just time as it is calculated on a clock meaning 60 minutes in every hour and 24 hours in a day
It’s usually advised to use Normal time when working on the actuals hours as to not confuse any one, when exporting the hours can be converted to decimal time for easier calculation when imported in the payroll. All of this depends on how your company’s policies are setup.
Changing from normal time to Decimal time
1) First you need to go to the Daily Summary

2) Afterwards you can right click on Grid in the window that opens

The hours will then convert decimal time as below
