H and HU cards are two different types of Smartcards. HU are the current set of cards. H were the ones previous to that. And for historic reference, the ones before that were F cards. The current DTV stream can be decoded only by H and HU cards. F cards were phased out numerous years ago.
Now, I'm sure you can guess what the other terms applied to these card types mean.
My friend (who is in the US) found the $70 deal and thinks this could be a good deal for him. Apparently it comes out cheaper than a previous quote he had for three regular receivers.
And if it matters to anyone, the coolest (fastest and best menu systems) receivers I've ever used are from Hughes. I've never seen a Tivo DTV yet - again, DirecTV is not available in Canada (only a couple of Canadian alternatives, the most popular one based on Dishnet hardware)
Bruno