There has been recent effort by a new community member to tag (in particular old) questions related to software installation with the software-installation tag. Since this also includes questions already tagged as package-management (see this example), I wonder how much these tags overlap and in what situations it is reasonable to have both present on a question.
I saw those edits today, and wondered the same thing -- thank you for bringing it up on Meta for discussion!
IMHO, package-management covers both the installation and the removal aspects (besides updates and searching & etc). Unfortunately, I think it would be a bit of a stretch to use package-management for tarball-type installs.
I could see keeping software-installation exclusively for "manual" installation (via
make install, for example) and using package-management when there's a higher-level program involved (