Summary
Wi-Fi is the wireless network inside the home. Ethernet is the wired connection that gives the cleanest test of the broadband line itself.
Definition
Wi-Fi connects devices wirelessly to your router and can be affected by walls, distance, interference, router placement, old devices and congested channels. Ethernet uses a cable from your device to the router and is normally the best way to test whether the broadband access line is performing properly. When judging a new home, test in two layers: first use Ethernet to check the service against the minimum guaranteed speed, then test Wi-Fi in the rooms where people will work, stream or game. If Ethernet is good but Wi-Fi is poor, the fix may be router placement, mesh, access points or cabling rather than a different broadband package.