Biz Dev is usually considered more prestigious because partnerships of one sort or another can move a lot of volume quickly or can create new opportunities that radically change fortunes. It also requires understanding business models, strategies, etc.
Sales might require an understanding of the user or might not. The company I work for does enterprise software and I seriously doubt our sales people know a whole lot about the user experience. They do know how to schmooze and most importantly how to be persistent and by persistent I mean continually bothering people. I have found discussions with BD professionals to be interesting and occasionally enlightening. Most conversations with salespeople annoy me - whether those conversations are a sales job or just sitting around chatting.
I've noticed also some startups don't call people sales people because then at conferences people aren't turned off by meeting a sales person. I'm not opposed to these tactics but just wanted to point out the functional/true differences.
Most startups are actually selling a better/different version of what does exist. Very few startups are truly category defining so as a result they are mostly doing sales. Business development as a result for most startups is really for getting distribution versus getting customers.