It would be nice if "module" had a single, specific meaning throughout the world of Perl, but it doesn't. In my experience, it pretty much always means a .pm file, but that file may or may not contain a package and, if it does, the package may or may not have the same name as the file. A module usually contains a package of the same name, but not always.
perlmodimplies a module is supposed to be name.pm with a package name declaration, but like many things, "supposed to be" and "actually is" may not be the same.