The term whiplash-associated disorder (WAD) was first used in 1995. A Canadian Task Force on Whiplash used this term to describe the cluster of symptoms that often occur after such an injury. Patients with WAD report neck pain along with dizziness and pain in other parts of the body.
Damage to the soft tissues of the neck such as the ligaments and muscles result in a cervical sprain or strain with WAD. The joints may be involved, too but there's no fracture.
The acute whiplash injury usually results in soreness of the neck muscles two or three days after the event. The symptoms can be mild to severe but go away within a few days to a week. Chronic pain and symptoms that persist resulting in loss of motion and function fall into the WAD category.
There is a difference between these two terms. The mechanism of injury is the same but the severity and duration are different.