Excuse me? That's a direct cut-and-paste from the apt-get man page.
It is, but it only half-answers the question. The original discussion
involved the difference between upgrade and dist-upgrade. The quote I cited
implied that upgrade is safer than dist-upgrade because upgrade doesn't
remove packages, while dist-upgrade may remove packages.
My comment pointed out that the apt-get man page entries for upgrade and
dist-upgrade do not justify that implication: the only distinction the
apt-get man page drawns between upgrade and dist-upgrade is between their
abilities to resove conflicts.
To fully answer the question, you have to also cut-and-paste the dist-upgrade
entry in the apt-get man page and point out where it is written that
dist-upgrade may delete packages. Then you can correctly conclude that
upgrade is safer than dist-upgrade with respect to deleting packages.
'upgrade' is not allowed to change the installation state of a package,
'dist-upgrade' is.
That may be true for apt-get (the apt-get man page entries for upgrade and
dist-upgrade mention nothing about installation state), but it doesn't seem
to be true for aptitude, where the man page suggests that upgrade may change
an unused package state from installed to not-installed:
Installed packages will not be removed unless they are unused