RS-422 and RS-485 are two types of serial communication standards used for data transmission over long distances. The main difference between them is the number of drivers and receivers that each one supports. RS-422 only supports up to 10 drivers and receivers, while RS-485 can support up to 32 drivers and receivers. Additionally, RS-485 has a differential signal that helps reduce noise interference, while RS-422 does not have this feature.