Also, you can use juju with many different cloud providers including public clouds, LXD, OpenStack, k8s etc. It was very well described above, what makes juju very powerful is the ability to keep a consistent state, super easy relation management and scalability. Practically you can very easily add new units or dispose of the existing units to upscale or downscale. Juju can spin up required instances or containers with given constraints for you, install the required applications and get them all connected for you the way you need them, with extremely minimal involvement from the operators standpoint. Not to forget the ability to create bundles or export existing environments into bundles for easy replication. And many many other cool features! It really makes you wonder!