Some years ago, it was easy to clone the current system partition of a Mac computer into a FireWire external hard drive and then use it as a boot disk for the same Mac or even for another Mac.
When I currently tried this with a USB drive (Western Digital Expansion +) and cloned the SSD of my MacBook and tried to boot another MacBook (different model) with it (holding down the option key during boot), it was not recognized as a possible boot disk
What could be the reason for this? Are USB drives more difficult than Firewire as boot disks? Or is it harder today to use the same system configuration on a different MacBook model?