just a little contribution to this instructive thread..
Have you read Of Symbol Tables and Globs by broquaint? You'll find very interesting.
The final comment of the article says:
So in summary, symbol tables store globs and can be treated like hashes. Globs are accessed like hashes and store references to the individual data types. I hope you've learned something along the way and can now go forth and munge these two no longer mysterious aspects of perl with confidence!