sealed vs vented subwoofers

I'd like to ask the forum what the primary differences are in sound, performance, and application of sealed powered subwoofers vs vented either bottom vented, rear, etc. B&W makes most if not all of their current line of powered subs sealed. Yet I see other manufacturers offer vented subs. What is the difference? Do the sealed subs produce a higher quality tighter controlled bass vs a more sloppy reverberating type of LFE out of the vented types? Thanks.