Sync speed is the speed of your broadband connection between the WiFi Hub in your home and Vodafone. When you check to see what speeds you can get with Vodafone, we show you the sync speed available at your address.
Download speed refers to the connection between your devices (like your phone or laptop) and your hub, within your home. Download speed includes devices that are connected through wires to your hub, and devices that are connected wirelessly over WiFi.
So when you test your internet speed over WiFi, the results you see will be your download speed and not your sync speed.