1.You could backup and restore an entire farm through PowerShell or CA.
(1)PowerShell
Backup-SPFarm -Directory <BackupFolder> -BackupMethod {Full | Differential} [-Verbose]
Restore-SPFarm -Directory <BackupFolder> -RestoreMethod Overwrite [-BackupId <GUID>]
(2)CA
Go to Central Administration -> Monitoring -> Backup and Restore -> Perform a backup.
Go to Central Administration -> Monitoring -> Backup and Restore -> Restore from a backup.
2.Per my research, VM snapshot/backup is not equivalent to SharePoint farm backup. SharePoint farm backup only backups all data about SharePoint, VM snapshot/backup backups all data in the VM, including other software data and system settings.
References:
https://www.nakivo.com/blog/vm-snapshot-vs-backup/
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