A herniated disc and a bulging disc are very similar or the same on some levels and on other levels, they can be completely different.
A disc bulge can be thought of as an inflamed disc that has a broader based outward expansion from its normal state. As the annulus pushes outward, contact and subsequent inflammation can occur in any nerves, spinal cord, or bony structures the disc comes in contact with. As this inflammation spreads, the pain from the disc bulge begins to include the nerves transmitting that pain to the brain.
A herniation is more of a canal that goes through the outer disc material which allows the nucleus of the disc to extrude through the canal and push against structures in the spine. The same result happens, depending on what structures are contacted and the degree of inflammation caused by the injury.
The resulting pain is diagnosed as a radiculopathy and have a prevalence of 35% of men and 45% of women having these at some point in their lifetime.
These disc events happen most often as a result of repetitive flexion events to the lower back at the disc level. One study (Adams & Hutton et al, Spine 1982) suggests that 28,000 repetitions of flexion are required to herniate a disc. If there is compression on the disc with flexion, fewer cycles are required to herniate a disc. So bending forward at the waist over a life time can cause this bulging.
There are levels of herniation that can happen. The worst being the sequestered disc herniation where the nuclear material pushes out of the disc and separates from the disc to become a free floating mass in the lower back. The only response to this condition is a surgical removal of the disc material. The most frequent type of herniation is where the disc material remains attached and in this case, taking the pressure off the disc (through adjusting or traction) will allow that material to be drawn back into its normal position where it will likely scar over and become stable over time. During this process it is imperative that the inflammatory process be reduced so healing can take place. Disc pain is generally characterized as a pain that goes from the lower back into the extremity as a result of involving neurology in some way. Occasionally a disc can be painful in and of itself, in which case it will feel like a deep localized sharp pain which is more intense in flexion and relieved by extension.
This is a fairly simplified look at disc herniation and the only true way to determine disc herniation is via advanced imaging techniques like MRI. Check with your doctor for advice on how to proceed with your lower back pain. Your chiropractic doctor works with these conditions daily and will be able to help you determine the next course of action.