In Backup and Sync, you can choose not to sync deletes between your computer and Google Drive. Here are the main differences between mirroring and streaming files from some Google support documentation:

You can also choose whether certain computer files will sync with the online version or if you’d like them to be disconnected. To access all your files, including those available offline, the Drive for Desktop app must be running.

Stream: When you stream, your MyDrive files are stored in the cloud, and you’re going to have to choose which among them you’d like to be available offline and taking up the least amount of hard drive space.

Files can be accessed anytime though, and you don’t need the Drive for Desktop app running to open the files as they can be accessed directly on your computer.

Mirror: When you mirror files, it’s basically like having all your content in two spaces you can access-online and offline.All your files are available offline and every change is synced online, so you both take up hard drive space and google storage space.

Drive for Desktop allows for files to be synced offline. While in Backup and Sync, you can only select folders to make available to your computer and be accessed offline. If you take a closer look, you’ll see that while both value file access convenience, Drive for Desktop has a greater focus on ensuring that users are working more around the cloud, offers more granularity in terms of sync capabilities, and provides better control over your cloud content. While Backup and Sync is mostly used to sync and store Drive locally on your computer, Drive for Desktop streams all your content from the cloud. Google Backup and Sync and Drive for Desktop have essentially the same objective: to provide a sync solution where users can access their files in a much more convenient way. While Drive File Stream is essentially the same with Drive for Desktop, Backup and Sync users need to note some key differences (and similarities) between the past features and today’s Drive for Desktop functionalities to adopt the new solution more easily. This tool will address IT management challenges caused by the confusion between their two previous sync solutions, Drive File Stream and Backup and Sync.

Google recently announced a unified sync solution for all their users called Drive for Desktop.

Google drive folder on desktop