gem41573 pretty much answered the question about the design similarities between the HSU and Outlaw subs.

The only real difference between the two, other than aesthetics,is that Outlaw chose the down-firing port design as opposed to the HSU rear-firing port(required for their optional "turbo boost" unit on their top models), which, in the case of Outlaw, gives you more placement options because you don't have to worry about minimum space near a wall.

Realistically speaking, when you look at the comparable similar units between the two companies(both sell excellent products), in my opinion, the Outlaw subs look better and are a little better value.