[digisign]

Depends on which Debian I believe, but Ubuntu doesn't update their package versions beyond security fixes within a single distro version.

So you'll generally want those fixes, unless they really broke something, which I'd guess would be somewhat rare.

[YokoZar]

Ubuntu also issues stable release updates (particularly to the latest LTS version) to fix regressions, major bugs, or occasionally update minor release versions. Some applications known to have good release procedures are also allowed updates (eg Firefox).