Vacuum or pneumatic

I was just recently told by a friend that the tubes you use at the drive up at the bank are pneumatic rather than vacuum. We then discussed this further because he tells me they are called pneumatic systems. The question then comes to whether an engineer named the system or a marketeer. An engineer will name it properly, but the marketeer will name it something kewl. So, I pose the question to you, the readers of my blog...does the bank system of tubes use air pressure to push the cannisters along or suction to pull the cannisters along?