The difference between the Magento Community & Enterprise edition?

Hello,
I am interested in starting up an e-commerce site. I heard that Magento was an excellent option and that there were two editions, with one (community) available as a free download under the open source system.
I would like know the differences between the Magento Community edition & the Enterprise edition in addition to the obvious cost associated with the Enterprise edition.
Help would be high appreciated.
Thanks.
