DateDiff

Return the time interval between two dates.

Syntax 
      DateDiff (interval,date1,date2[, FirstDayofWeek [, FirstWeekofYear]])

Key
    date1      The first date to compare

    date2      The second date to compare

FirstDayofWeek A constant defining the first day of the week:
               vbUseSystem (0), vbSunday (1=default),vbMonday(2), 
               vbTuesday(3), vbWednesday(4), vbThursday(5),
               vbFriday(6), vbSaturday(7)

FirstWeekofYear A constant defining the first week of the year:
               vbUseSystem(0), vbFirstJan1(1),vbFirstFourDays(2),
               vbFirstFullWeek(3) 

    interval   The date/Time interval to express the result:

                 yyyy  Year
                  q    Quarter
                  m    Month
                  y    Day of year
                  d    Day
                  w    Weekday
                  h    Hour
                  n    Minute
                  s    Second

Example

dtm1="18-Feb-10"
dtm2="19-Aug-10"
WScript.Echo "Difference between " & dtm1 & " and " & dtm2
intMonthsDifferent=DateDiff("m", dtm1, dtm2)
WScript.Echo intMonthsDifferent

“Listen to many, speak to a few” ~ William Shakespeare

Related:

Date - The current system date
DateAdd - Add a time interval to a Date
DatePart - Return a unit of time from a date
DateSerial - Return a Date from a numeric Year, Month and Day
Weekday - Return the day of the week
Equivalent PowerShell cmdlet: New-TimeSpan