The competition between cable companies and satellite TV providers is nothing new, as they have been gunning for each other for quite some time now. Sometimes the marketing campaigns can get downright ruthless, grabbing for the throat and trying to convince customers that they must switch immediately. The truth of the matter is that any time one of the two brings in a new technology or adds a new channel, the other is quick to respond and try to keep in the hunt for #1. Over at http://www.cable-tv.com/directv-vs-cable/ they have attempted to break down the difference, but a lot of it really boils down to personal preference and availability.
Of course availability is really one of the big differences in the comparison, as cable companies must have an infrastructure in the local area in order to handle customers. DirecTV on the other hand can handle any customer that has a clear view of the sky, which means they can cover many rural areas and other isolated locations that are unable to get any service otherwise. Of course the other advantage is that DirecTV has the ability to provide huge benefits and technology that many smaller companies cannot do because of the overhead costs.
Ultimately when it comes down to comparing a company like Comcast or Cox, they are fairly competitive with DirecTV. However, DirecTV does their best to gain little advantages that can really be a big deal to some customers. For example their promotions provide free tech upgrades and premium channel trials can be a great motivation for switching over, while things like their exclusive deal to get NFL Sunday Ticket often keep customers there on a permanent basis. The bottom line is that every company has a wide variety of plans and investigating them all can help you to find the best deal, so research and make a decision that is specific to you.