What is the difference between having a bulging disk and a herniated disk?

Size: Bulging discs are normal findings on imaging studies while disc herniations are discs that have moved out of there normal position. Disc bulges do not cause symptoms. A disc herniation is an actual passage of the disc's inner core or nucleus passing thru the outer part or annulus of the disc where a disc bulge does not result in any part if the disc out of its normal alignment of material.

Disc bulge herniatio: A bulging disc occurs with degeneration or minor disruption of the disc complex. A bulge usually doesn't contact or compress the spinal cord or nerve root and can be an a symptomatic finding. A herniated disc is a bigger disc disruption usually associated with mass effect on the spinal cord or nerve root. Weakness, sensory loss, or pain down the extremity is usually found.

Herniated disk: Very much the same but herniated generally connotes greater disc extrusion with greater potential for affecting spinal nerves.

Synonyms: The terms bulging disk, slipped disk, herniated disk are roughly the same idea that they disc has moved out of place where it should be and possibly compressing nerve or spinal cord. Typically though herniated disk signifies a slight increase in severity of pathology over a bulging disc. It gets a little more specific if terms like disc protrusion and disc extrusion come into the mix.