Google Apps Education Edition

I'm exploring using this with my Middle School students next year but the more I read the more confused I get. What are the primary differences between the Team Edition & the Education Edition?

How does the email work with the Education Edition? Is email delivered to both gmail & the school domain?

Can you restrict students to only certain portions of Google Apps or do they automatically have access to everything?

I don't want to try this because I don't want to assign our domain to anything without knowing how all of this works. I'm not even sure of all of the questions to ask. Does anyone have an example of how they're using this in a Computer Lab with multiple grade levels?

Help?