Also, a different design for people who have a preference for a more elegant style. You could also say that it doesn't have handles.
Included is a 5.25" to 3.5"or 2.5" adapter.
http://www.bitfenix.com/global/en/products/accessories/spectre-pro#specs
It's on our product page :) 5V
It's not much louder. 2 decibels. They're the same blade size, one is 230mm x 200mm x 30mm, one is 200mm x 200mm x 25mm. The wider blade has its benefits (better airflow and silence)