You’re thinking of apt full-upgrade. dist-upgrade is the old name for it.

The only difference between upgrade and full-upgrade is that full-upgrade will delete packages if necessary (like if you have a program installed that conflicts with a new version of another program), whereas upgrade will never do that. upgrade is safer for day-to-day updates.

If you do an upgrade and there’s packages that need you to run full-upgrade, you’ll see a message saying that some packages have been held back.

full-upgrade is mostly safe. You just need to read the output carefully before continuing.