Microsoft VDI 2012 - VDI Personal collection vs Session-based deployment

I have a small confusion about the differences between the 2 types of set ups:

When deploying using Add Roles and Features the Wizard requests to choose from one of two Deployment Scenarios:

• Virtual machine-based desktop deployment : Virtual machine-based desktop deployment allows users to connect to virtual desktop collections that include published RemoteApp programs and virtual desktops.
• Session-based desktop deployment : Session-based desktop deployment allows users to connect to session collections that include published RemoteApp programs and session-based desktops.

Although this seems intuitive now, if I continue with "Virtual machine-based desktop deployment" I later have another two options when creating a collection:

• Pooled virtual desktop collection
• Personal virtual desktop collection

This is where my confusion lies. What is the differences between a Session-based deployment and Virtual machine-based deployment with Personal virtual desktop collections?

I'm mostly finding information pertaining to Windows Server 2008 but I know there are some core improvements in VDI 2012 so would someone please comment on that.

Thank you

Session-based

Session-based refers to Microsoft’s implementation of session virtualisation, isolation which is what was previously called Terminal Services.

• Each user runs on a server operating system (OS) desktop that is semi-isolated from the other user.
• Each session shares the same OS kernel.
• A RDS server is normally a locked down secured environment because configuration changes can affect all users.

Virtual machine-based

Virtual machine-based refers to full x86 hardware virtualisation where:

• Each virtual machine runs separate virtualised hardware that is then interpreted and mapped to physical hardware. This runs on one or more Hyper-V servers.
• Each client connects to a separate operating system environment running a client OS like Windows 8.
• Client Oss are normally secured the same as a regular Management Operating Environment (MOE) base changes don’t affect other users because they run in a separate OS instance.

The different between Pooled and Personal for Virtual machine-based is that:

1. Pooled shares VMs between users. When a user logs off that VM is available for another person to use or can be rebuilt. This is good for regular users that use a lot of the same applications. http://technet.microsoft.com/en-us/library/dd883265(v=ws.10).aspx
2. A Personal VM is only used for one user. This is good for power users that require specific applications that might be manually installed. http://technet.microsoft.com/en-us/library/dd883277(v=ws.10).aspx

This link and it’s sub-links give some examples: http://technet.microsoft.com/en-us/library/hh831447.aspx

Also see:

• http://technet.microsoft.com/en-us/library/dd736539(v=ws.10).aspx
• http://www.microsoft.com/en-us/server-cloud/windows-server/virtual-desktop-infrastructure-features.aspx

Hope that helps.