These are the various date and time related blocks available in the Time group of the block library:

date: extracts just the date portion of a date time value

dateTimeAdd: adds a duration (hrs, mins, or secs) to a dateTime

dateTimeSub: subtracts a duration (hrs, mins, or secs) from a dateTime

dateToNumber: converts the date into a number

dateToString: converts a part of date into a string

dtToDtAdd: adds one dateTime to another dateTime; results in a duration of minutes or seconds

dtToDtSub: subtracts one dateTime from another dateTime; results in a duration of minutes or seconds

now: gets the current dateTime for the host

siteDateTime: gets the current date and time for the site associated with the target Ref of the bline program

time: extracts just the time portion of a date time value

timeToMinutes: converts a time value to a number of minutes 

timeToTimeAdd: adds one time to another time; results in a duration of minutes

timeToTimeSub: subtracts one time from another time; results in a duration of minutes

Some blocks have inputs or results in dateTime format, while others in simple time format. Blocks that require a time format input might not work if a dateTime value is used as the input.

dateTime example:  2019-07-04  14:39:15:149   (date and time with milliseconds) 

time example: 14:39:15  (just hours:minutes:seconds)

The Blocks can be found in the Block Library in the Time group.