Note: Drive File Stream is now Drive for Desktop.
At the beginning of 2021 Google announced on their blog, that Google Backup and Sync functionality (including the users as well) will be transitioned to a new version of Drive for Desktop.
If you are looking to use Google cloud services and sync files between Google Drive and your computer then you can use Backup and Sync or Google Drive for Desktop.
According to Google, they had two cloud sync clients available: Drive File Stream (for business users), and Google Backup and Sync (for consumer users).
In 2021, Google will merge these two cloud solutions, taking the most used features from both, and combining them into one cloud sync client.