The big difference between leasing a receiver from DTV and buying it from them is the contract. When you lease the receiver from them, you pay a small amount upfront for the receiver, are under a contract for 2 years and if you stop the service at any time (even after the two years), you have to return the receiver.
If you buy a receiver from Direct TV, you pay a BIG price upfront for the equipment, but you can stop service anytime with no contractual agreements.
Having said this, we all know that different DTV representatives seem to give out different information. This is what I was told 2 years ago from the rep I spoke to.
Let us know what you find out!