I reffer to the Parthian and Sassanian heavy horse as cataphracts. I don't understand the Greek and Latin classifications, and seeing as how many of the Parthian heavy horse were still considered cataphracts though they couldn't afford horse armor, and while a greater number of Sassanians were heavier when compared to the Parthians, for most of the time the basic tactics were the same, though evantually horse archers lost prominence and infantry gained prominence.