HD Sharpness not great! - DirecTV

We're away from home this week and watch HD TV on the same TV (Vizio) we have at home, but it/s so much sharper than we have at home. We've noticed that when we're in Bust Buy that the TVs there are much sharper, but thought they were newer tvs. I am now wondering if we are not really getting actual HD in our home or need to adjut the tv settings! We are so enjoying the better view and want to get it at home. What do you suggest>

This question, "HD Sharpness not great!," is about DirecTV channels, programming, equipment, and sports.