Plate armor is a rigid carapace of metal, providing excellent protection at the cost of fine dexterity and speed. If you do not have proficiency in Plate armor, you grant advantage while wearing it, and may not gain advantage. You must be proficient in Chain armor before you may gain training in Plate armor.
Half plate is a rigid metal breastplate, girdle, shoulder guards, vambraces, gauntlets, and boots, providing excellent protection at the cost of fine dexterity and speed. If you do not have proficiency in heavy armor, you grant advantage while wearing half plate, and may not gain advantage.
Fullplate is a rigid carapace of metal, providing excellent protection at the cost of fine dexterity and speed. If you do not have expertise in heavy armor, you grant advantage while wearing it, and may not gain advantage.