According to Google, ”Drive for desktop is an application for Windows and macOS that lets you quickly access content directly from your desktop, helping you easily access files and folders in a familiar location. Drive for desktop also automatically syncs local files to the cloud in the background, which minimizes the time you need to spend waiting for files to sync.”
Basically it sounds like Google has taken features from the previous versions of its desktop apps and combined them into a single solution. In a way this is true because according to Google, prior to this they had two versions of the desktop app where Backup and Sync was aimed at consumer users, while Drive File Stream was more for the enterprise, but now that Workspace is open to all users, Google has combined the features together.
For those who are still using Backup and Sync, Google states that this will stop working on the 1st of October, so you’ll want to download this new application ASAP.