はい、VBS の DateDiff 関数を使用してこれを行います。
http://www.devguru.com/technologies/vbscript/quickref/datediff.html
DevGuru情報
DateDiff(Interval, Date1, Date2, FirstDayofWeek, FirstWeekofYear)
The DateDiff function calculates the amount of time between two different dates.
There are three mandatory arguments.
Interval
The Interval argument defines the the type of time interval you wish to use to
calculate the time difference.
Only the following settings can be used. You must place the setting inside a
pair of double quotes.
| SETTING | DESCRIPTION |
|:--------|:-------------|
| YYYY | Year |
| Q | Quarter |
| M | Month |
| Y | Day Of Year |
| D | Day |
| W | WeekDay |
| WW | Week Of Year |
| H | Hour |
| N | Minute |
| S | Second |
JavaScript では、次のようにできます。
JavaScriptで日付差を計算する方法