This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
I think what you probably actually read was that you have the ability to gain direct access to the hibernate API if you need to. It's not that you'd normally choose one over the other. You use GORM for 95% of everything you do. For that 5% where GORM just isn't cutting it you can gain access to the hibernate session, write your own queries, whatever. But only if you need to.