Both Bluetooth and Wi-Fi allow you to connect the coffee machine and mobile phone so that you can control it remotely. The difference is that:

• Bluetooth relies on the Bluetooth technology to connect and communicate with the coffee machine locally without the aid of the Cloud (hence you don't need to create a user De'Longhi account to use it). Bluetooth technology has a small range, for this reason, you must stay close to the coffee machine to control it remotely.
• WiFi instead relies on the internet connection and your Home Wi-Fi network to communicate with the Cloud and the coffee machine, so you need to create a user De'Longhi account to log into the app and then control your WiFi machine. Moreover you can control the Coffee Machine from a wider distance.