* Packages are perl files with .pm extn and is considered a separate namespace. So a package is nothing but group of related scalars,arrays,hashes and subroutines for a specific purpose.

Once a package is included in a .pl file (using "use") and you want to call one of the subroutines of the package, you may have to use the scope resolution operator &package::subroutine1

* Modules are packages but which has the capabilities of exporting selective subroutines/scalars/arrays/hashes of the package to the namespace of the main package itself. So for the interpreter these look as though the subroutines are part of the main package itself and so there is no need to use the scope resolution operator while calling them.