From what I can tell Date and DateTime have the same functionality. Is there a reason why I would want to use one instead of the other?
In VB.NET Date is an alias to System.DateTime, so yes, they're the same thing. You can see all the aliases in this chart on MSDN.
C# has no Date type, but DateTimes do have a Date property which returns a DateTime with all of the time-related fields cleared out.
Specifically it returns:
A new object with the same date as this instance, and the time value set to 12:00:00 midnight (00:00:00).
VB.NET does have a Date type but it is equivalent to a CLR DateTime