The major difference is instead of using a traditional package manager (DNF) it has a hybrid package / image system with rpm-ostree. Not only does it install / update packages, it also creates snapshots after every incremental update. Any RPMs installed are layered on top of a universal base OS image (which can easily be undone).

This makes it quite easy to roll back updates if something breaks as you can just boot into a previous image in grub. It essentially is similar to a git repository and you can easily revert changes in your ‘repository’ should they cause issues. You can also quite easily switch to a different branch (e.g Rawhide [The development version]) and then revert back when you’re done testing or even switch to a different release (e.g. to Sericea [Sway] or Kinoite [KDE])

Another major change is the root volume is read-only, increasing resilience to accidental damage or potentially malicious attack as well. This immutable nature is similar to what you could find on Android, ChromeOS or macOS (after a specific version which I forget).

Of course this is not without its downsides. You most definitely can have some more customization options on a more traditional OS that is not immutable. The snapshot feature after package updates has also been done in other traditional distros, I believe OpenSuse would be an example since I think Zypper automatically creates a btrfs snapshot with snapper. I also think there was a dnf plugin for this but I don’t remember well enough. Lastly in Silverblue updates are only applied after a restart which is not necessarily ideal if you are coming from a distro that does online updates.

So really you’d only pick Silverblue if you benefit from having snapshots after each update, are ok with flatpaks, and want an immutable file system for reliability / potential security. There definitely is value in a Fedora Workstation setup that mostly has flatpaks, but that is only a good choice if you don’t wish to use rpm-ostree’s snapshot feature and you don’t want the benefits and downsides of an immutable file system. You can always layer Distrobox as well, but I am unsure as to how invasive it is. I hope my answer was not too convoluted.