what is the difference between "var" and "vardir"

The Formal Form

vardır - definitely, surely
The formal form acts a statement of fact and is suffixed with the verb - to be - -dir
As already mentioned above - vardır - means - Is (definitely) existent, It (definitely) exists, There (definitely) is, There (definitely) are. This form is used in Public Notices and Advices.

Here is an actual example from a Traffic Propaganda Advertisement seen in Manisa, Turkey, May 2006
Unutma! Her trafik kuralının bir nedeni vardır.
Don´t forget, every traffic law has a reason..!
Thus showing - vardır as definitely, surely.