Another difference between the Rev3 and R4 WiFi is the number of their serial ports and I2C buses. The Rev3 has a single serial connection, shared by the USB port and the RX/TX pins. There's also ...

Another major difference between the processors of the Nano and Uno is that the Uno's is removable. If you somehow damage it, you can readily pull it out of the DIP (Dual In-line Package) socket ...