A module is a .pm file containing some Perl code. A package is a declaration of the name of the current scope, e.g.:

package Math::Complex

which can occur in the code of a module or a script. A module can be used, because it is a physical 'thing', but a package cannot. A module may contain several packages: CPAN does this. The advantage is that the code inside that module can still be chunked up into classes/etc. by package declarations, as if these classes were separate modules, but that the functionality is still lumped into a single convenient file.

Please note that package is scoped:

package Foo;
print __PACKAGE__,$/;

{
  package Bar;
  print __PACKAGE__,$/;
}

print __PACKAGE__,$/;
__END__
Foo
Bar
Foo
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with the default scope being the file, or course (although you rarely have to think about things like that, fortunately).

polypompholyx has it right. Some of your confusion may be related to the way that barewords are translated into filenames when Perl looks for a module. For example, 'use Math::Complex;' signals Perl to search for the file 'Math/Complex.pm' in @INC and to load it if found (or die with an error if it can't be found).

But even if the module Math/Complex.pm is found, it may or may not contain the package declaration Math::Complex. For example, it could have a typo:

package Math::Compelx;

# blah, blah, blah

1; # modules need to return 'true'
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Or it could have multiple packages:

package Math::Complex;

# blah, blah, blah

package Math::Complex::Private;

# blah, blah, blah

1; # modules need to return 'true'
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A module is a file of code, or a tree of bytecodes. A module could be precompiled (.pmc), uncompiled (.pm) on disk; or pre-loaded in memory as one unit -- assuming no autosplit.

In summary: packages are about namespaces, and modules are about files. They are different things, like apples and boxes -- until the day when you start placing one kind of apple into one kind of box, and people start thinking that apples and boxes are related. And they are! but still, one in fruit and the other is a type of container.

Hi refer this,

difference between packages and module

Packages and modules