Sounds like cloning.
However, this won’t always work without issues, because different machines have different stuff and when you save, for example, network settings then they probably won’t be correct for a different machine.
The safest way I would suggest for you is to create a good ol’ backup.
See Q5:
If you create a plain old backup, you can select what’s backed up, etc. Usually, it’s enough to save to your home folder. Sometimes you can even add /etc and similar. However, as previously mentioned, it’s important to not restore too much, when settings simply won’t match in a different environment.
If you, however, want to create a persistent Live USB Stick, i.e. a stateful OS put onto a portable storage medium, then you can do something as written in the following article.
https://www.howtogeek.com/howto/14912/create-a-persistent-bootable-ubuntu-usb-flash-drive/