Both free versions are fine for occasionally creating a bootable backup. The full versions allow you to schedule updates on a regular basis and update backups with new changes only.
Both offer free limited versions, and full versions for $30 and $40, respectively. There are two main Mac options for creating bootable backups: Super Duper and Carbon Copy Cloner. You can technically use Disk Utility to copy your entire hard drive, but the result will not be bootable on an external drive. All files on your external drive will be deleted during the backup, so don’t use your Time Machine drive or a drive you use to store important things on. You’ll need two things to create your bootable backup:
