What exactly is the difference between an alias and a reference?

You have to de-reference a reference , but not an alias.

However, I am wondering how can I create an alias explicitly (without using any extra module).

Use foreach :) or map or grep ... or use a sub, @_ is always aliased, but as soon as you make a copy, the alias is broken

Unless you use a module from cpan, you can't go nuts with aliases