Datetime
The DateTime objects in C# are immutable they cannot be modified once they are created
When we don’t specify the time it defaults to 12:00:00 AM
Custom date and time format strings | Microsoft Docs
Timespan
It is an immutable datatype similar to DateTime
The difference between two DateTime objects is always a TimeSpan
The Total methods will return the value of the time span object in the selected units.
The Parse Method can be used to convert a String to a TimeSpan Object