What will be different, besides the pricing, will be that episodes will now be streamed, within the cloud, and not downloaded, following the broader industry trend led by Netflix and Hulu.
Although still unconfirmed, the upcoming Apple TV is said to use iOS 4, the operating system used on the iPhone. It will also use flash memory, moving away from the HDD seen in the original model.
Because the device will ship with (likely) under 128GB of flash memory, downloading makes little sense when streaming can be done efficiently.
Apple's iTunes platform remains the clear market leader for music and movie/TV downloads, so Apple should have significant clout with content producers whilst trying to get them to drop the price of rentals.