What exactly does "installing a package" mean?

[Marcin Borkowski]

Hi all,

do I get it correctly that "installing a package" means that Emacs
creates a certain subdirectory of `package-user-dir' and puts the
relevant file(s) there - and that's it?

In particular, is deleting a subdirectory of `package-user-dir' enough
to uninstall the package?  Is moving its subdirectory somewhere else,
restarting Emacs, then copying it back again and restarting again
equivalent to uninstalling and then installing again?

The reason I'm asking is that I'd like to get rid of the mess I managed
to introduce in `package-user-dir', but OTOH this mess is working, and
I don't want to break something accidentally, or rather, I want to have
a simple way to rollback any changes.

TIA,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University