The Samnites comprised several tribes of native Italians who inhabited the central spine of the Italian mainland. They were fiercely independent and for several centuries fought against the emerging power of Republican Rome. During the Second Punic War, they allied themselves with Hannibal and the Carthaginians and formed a major part of his army. After the close of the Punic Wars, the Samnites formed separate legions and fought as allies/subjects of Rome. For each Roman legion, there was at least one allied legion present.
The Campanians were originally Greek colonists who settled on the west coast of Italy in the region of Capua and Naples, south of Rome. Generally, they were allies of Rome, their cavalry being very good. They also supplied mercenaries to Sicily and the Carthaginians. Eventually they were absorbed into the ever expanding Roman state.
Samnites arms and armour were distinctive. Short tunics, some breastplate armour, Italian style helmets, various styles of early scutum shield and javelins were their usual weapons.
The Campanians equipment was more Greek in style with more ornate additions to hemets. Infantry was Greek hoplite type.