Three things: physical size, room size, and rolloff.
The SB16 is a little smaller than the ported version, which helps in dual placement situations... but, also, the sealed sub has a much ore shallow rolloff than a ported sub, which really plays well to a mid-sized room. Room gain plus the shallow rolloff will help with super deep extension.
Does it have a more musical nature? In my opinion, sealed subs tend to sound tighter. But, I guess that is more subjective than anything...
Just keep in mind, we're talking about dual subs, which equates to a ridiculous amount of power and headroom! ;-)