OTA


It depends.

Fastboot ROMs are manually updated with the help of your PC.

Recovery ROMs are OTA as in you can do everything with your phone, it is an updater app that download the file, and then reboot to recovery to install the ROM. It works perfectly for my phone, but the process can fail at different levels, so you may need to download the file yourself, and/or go to the recovery and manually install.
 
It depends.

Fastboot ROMs are manually updated with the help of your PC.

Recovery ROMs are OTA as in you can do everything with your phone, it is an updater app that download the file, and then reboot to recovery to install the ROM. It works perfectly for my phone, but the process can fail at different levels, so you may need to download the file yourself, and/or go to the recovery and manually install.
It is worth mentioning that some countries like Brazil, Mexico, Turkey and Egypt are blocked by MIUI.eu to receive OTA updates.