These were the biggest points:
Here's a look about what Intel has to say about Hyper-Treading on the Nehalem:Nehalem is an entire family of products that span from Server to Mobile. Fast by design with quicker connects between cores and greatly improved memory bandwidth. Hyperthreading greatly improves efficiency. Power Management has been GREATLY redefined from previous chips both through new techniques as well as physical transistors being changed.
And the new cache system: