Arduino WiFi Shield: http://arduino.cc/en/Main/ArduinoWiFiShield
Arduino Ethernet Shield: http://www.arduino.cc/en/Main/ArduinoEthernetShield
Tutte e due riportano:
Operating voltage 5V (supplied from the Arduino Board)
E comunicano attraverso:
Connection with Arduino on SPI port
Quindi possono funzionare senza problemi !
Serial Peripheral Interface (SPI) is a synchronous serial data protocol used by microcontrollers for communicating with one or more peripheral devices quickly over short distances.
Penso che sono stato esauriente ! 