At its core, Netflix's business consists primarily of interfacing with subscribers via the Internet and sending them DVDs via US mail. Its only major competition for this business comes from the mostly similar online rental service run by Blockbuster. The two companies are more or less competitive in terms of price, but there are differences in what customers get.
Netflix's library of titles is bigger than Blockbuster's, which is of great importance to lovers of hard-to-find movies. Also, Blockbuster does not offer any titles via streaming, but it should be kept in mind that so far the majority of Netflix subscribers don't use this capability, even though they could do it at no extra cost.
Netflix has more than twice as many shipping points as Blockbuster, which should mean that average shipping time will be less for some customers. But Blockbuster subscribers can receive a disc by mail, then return it to a brick-and-mortar store, which should usually speed up receiving their next disc in the mail.
In general, the principal advantage to choosing Blockbuster is that they offer subscription plans which permit customers to rent a mix of online and brick-and-mortar-store discs (including video games at a discount). Since Netflix has no brick-and-mortar stores, this is a capability they can't match. The customer who wants a very high volume of rentals, particularly new releases, will probably be happier with Blockbuster. However, this conclusion assumes a customer who has no problem with going to a brick-and-mortar store frequently.
