What is the difference between a stress fractures on the metatarsal and metatarsalgia?

Nothing: The difference is in severity of pain. This is a more common cause of forefoot pain than morton's neuroma.

Several: A stress fracture is a break/crack in the cortex(shell) of the bone. It can lead to a omplelete fracture if care is not taken to protect the foot from additional trauma/overuse. Metatarsalgia is an inflammatory process. This can sometimes proceed a stress fracture. Both need to be treated to prevent more serious injury. See your foot doctor. Dr l.