What is the difference between tender points and trigger points?

Both trigger points and tender points describe regional muscle tenderness. In some situations, there's not much difference, but we tend to refer to multiple tender muscles in the context of fibromyalgia as "tender points" and isolated regions of muscle tenderness in patients without generalized tenderness as "trigger points." The latter have a better long-term outcome and tend to represent the "hot spot," as it were of the patient's regional muscle pain. The tender points are just one of many regions that are tender in fibromyalgia patients.