the ATmega ones have an actual serial connection on-board. For instance, on the Nano there is an FT232RL between the USB connector and the microprocessor (on an Arduino Uno board, a small ...

A second difference is that Minima has the Renesas MCU debug bought out to connector called ‘SWD’ for connection to an external debugger, while on R4 WiFi the Renesas MCU debug port is taken to the ...