When trying to set up a condition that checks whether 1 jobs last trigger date/time is less than the current date minus a few hours, we need to be able to compare the {TRIGGER(Active|LastTrigger|LastRun)} to {DATENOWADD(Hours|-8|yyyy/MM/dd hh:mm tt)} using variable. There is no variable types available to compare these. Currently only Boolean, Int32, Int64, Double, Decimal and String are available. We need a DATE type.

Yes, I am also looking exactly for a date/datetime comparison
How else can I check if the execution date time of a task is within a range of few hours?

Old post, but still showing up in search results.

I format the date-times as a decimal (yyyyMMdd.HHmmss) then can use a Decimal comparison for the Task Condition. So if I want a Task to be skipped if the previous task has run within the last 2 hours I would do:
On Start - If Other Value
{TASK(PrevTask,LastRun,yyyyMMdd.HHmmss)}
Decimal - Larger (>)
{DATENOWADD(Minutes|-120|yyyyMMdd.HHmmss)}
Continue to next Task in order