Xiaomi and Redmi chargers can be universal, can be used to charge each other, as long as the use of standard Micro USB interface of the phone, the charger and data cable can be universal. It should be noted that some mobile phones currently use a USB Type-C interface, so that the data cable can not be directly used on the Micro USB interface of the mobile phone.
The chargers of Xiaomi mobile phones and Redmi mobile phones can be generalized, because they generally belong to a company's serial production brand and production line, so their charger power and frequency as well as the line used are basically universal