An upgrade to Google Wifi in most ways, a Nest Wifi starts with a router and can be expanded with additional routers or mesh points. The router connects to the modem and has a larger coverage area while the points simply strengthen the mesh. The points also have a smart speaker built-in for Google Assistant.
Google Wifi has long been one of the best options for a simple and reliable mesh Wi-Fi setup. While lagging behind Nest Wifi in raw performance, the price advantage means you can more cheaply blanket a home with a lot of interference while keeping speeds high enough for most people.