What's the difference between /usr/(lib|share)/(perl|perl5)?

Hi all.

Can someone tell the difference between:

/usr/lib/perl
/usr/lib/perl5
/usr/share/perl
/usr/share/perl5

and the corresponding dir with the /usr/local prefix (or tell a
relevant link)?

I know about @INC, that in my system (debian etch, perl 5.8.8) returns:

/etc/perl /usr/local/lib/perl/5.8.8 /usr/local/share/perl/5.8.8
/usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.8 /usr/share/perl/5.8
/usr/local/lib/site_perl

I noticed that CPAN seems to install modules in
/usr/local/lib/perl/5.8.8

but frankly I can't actually tell the difference between modules
installed in all these various directories (apart from the obvious fact
that /usr/local is used for installing modules not managed by the
package management system).

In particular where am I supposed to put modules used by scripts that
only have to run in my system, and where am I supposed to put
modules in a source perl package (/usr/local/share/perl,
/usr/local/lib/perl, /usr/local/share/perl5, /usr/local/lib/perl5 ?).

Many thanks in advance
Cheers
--
Stefano Sabatini
Linux user number 337176 (see http://counter.li.org)
.