When the computer crashes the OS can rollback to a restore point.
Only OS and app file will be restored
Make sure you run an antivirus before creating a restore
You should create a restore point before updating or replacing the OS, when an app or driver is installed, manually at any time.
This is like a restore for data.
When backing up you only need to back up the stuff that has changed
Types of backup
Normal backup backs up files since forever.
Differentual backup takes longer but restoring is effectively one click.
Incremental backup backs up files since last backup, faster but restoring is slower because you have to restore every single increment