I found something weird when I was using “apt-get”: for some packages, usually the linux kernel packages, they won’t be upgraded when I use “apt-get upgrade” command, but they do been upgraded when I run the upgrade from the “Update Manager” program. Why?
Today I google it(“apt-get not change update manager works”) and found the answer from here.
Was my desktop activity equivalent to my server activity?
Most of the time, yes, the desktop update is equal to apt-get update && apt-get upgrade.
However, apt-get upgrade will not install packages like kernel upgrades that are optional but highly recommended, while Update Manager will. You have to use apt-get dist-upgrade for that, in which case you would have a true equivalent.
If you use apt-get upgrade and kernel upgrades, etc. are available, you will see a message like The following packages have been held back:; that’s your cue to run apt-get dist-upgrade if you wish to upgrade those packages.
Note that a number of types of cloud servers do not use their own kernel, but their physical “host” machine’s kernel (OpenVZ, vserver, LXC, Xen paravirtualized); other types behave like physical machines themselves (Xen HVM, KVM).
This answer well explains my question.