apt-get upgrade与dist-upgrade的区别

The upgrade option only installs new version of the packages that are already installed on the system (and yes, kernel updates belong to them).

However, sometimes the updates change dependencies: for example, a new version of a package will no longer depend on a library that you have installed, or will require installation of additional libraries. Theupgrade option will never remove installed packages that you no longer actually need.

However, the dist-upgrade option can "intelligently" handle changes in the dependencies system. This includes removing packages that are no longer necessary or resolve conflicts between packages that arose because of changes in the dependencies.