Can someone please explain to me what is the difference? Or if they're equals, but one is "righter" than the other one?
For example: I've seen something like
The first part
namespace_module as the alias for your blocks, models, helpers you define in your
<blocks> <namespace_module> <class>Namespace_Module_Block</class> </namespace_module> ...
The second part after the slash gives you the exact block/model/helper of your extensions. The
/ replaces the class type (
_Model_, ...) you want to load.
For your example
namespace_module/helper it means Magento should load (in case of a block)
Same for models and helper classes ...
... will load ...