Data Transfer different from Bandwidth in Cpanel?!

In cpanel it states:

Monthly Transfer
3684970.69MB which is around 3TB

BUT,

When I click on AWSTATS for a particular site it says:

Bandiwdth for the month is: 26473.98 GB which is more like 26TB!!

So what is it?!

Even on the bandwidth page it states the site is only using 3571.88 Gig bandwidth.

I am in the process of buying a dedicated server so this is very important!

cpanel tracker I believe uses a monitor to track usage. AWStats analyzes the log file. If the request and response don't have the correct sizes (ex: streaming could cause a problem) then it will be off.

So what one should I believe?
I do have streaming video and AWstats says it is using 13383.51 GB which is more than the cpanel total of transfer!!

I need a dedicated server but dont know if I should get a 10TB or unlimited because of these mix up in stats.

AWSTATS just assumes , Cpanel knows