I am just reading [this document](http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.prd29-genc-009492c/index.html) from ARM on **TrustZone** and some things are unclear to me.

The fact that a **Hypervisor** offers a special CPU mode and that for the **TrustZone**, the processor comes with an extra *33rd bit*: Isn't mode also a particular bit setting? How is then an extra bit making all that difference in terms of security. I do understand that the extra bit makes way for two separate 32 bit address spacing, but apart from that I am unable to put two and two together. Can someone clearly explain why **TrustZone** is more secure than a Hypervisor??