A disc herniation happened when the disc material has broken through the exterior wall of the annulus fibrosis and is sitting on the neural canal. If it is sitting on the nerve, there will be constant pain as the disc is herniated and does not have the ability to bulge back in. Disc herniations typically will respond to an exercise program being careful not to overstretch this structure to create more symptoms.
A bulging disc, the disc material begins to creep backwards and put pressure in the posterior aspect of the spine. The posterior aspect of the disc is highly sensitive and pressure on this nerve is painful. Progression of this leads to sciatica symptoms. Disc bulges will typically respond to an exercise program as well.