What is a logical name in sleep mode?

I am new to hibernate and have a hard time understanding what is boolean name usage in hibernation? I read this http://docs.jboss.org/hibernate/orm/5.2/userguide/html_single/Hibernate_User_Guide.html#PhysicalNamingStrategy

and he says:

The single contract, NamingStrategy, effectively combined the separate issues that are now modeled individually as ImplicitNamingStrategy and PhysicalNamingStrategy.

I don't understand what two problems are being talked about here? As far as I understand, we have a schema like this: Java entity class attributes -> logical name -> physical name. Why do we need a logical name? It says there are 2 stages, why do we need 2 stages?