There is a difference between a crack and an exposed tape joint. This is a crack or tear as engineers like to call them. A tape joint that is exposed is more common and less serious. It takes little movement to open up a tape joint. A tear or crack however is a fracture in a section of sheet rock that was once whole. The area at where a tape joint opens or comes apart never was whole. It's a place where two pieces of sheetrock (or wallboard) simply rest side by side. It takes more stress to create a fracture in a whole piece of sheetrock than it does to simply open a tape joint.