Is the DirecTv HD service comparable to Blu-ray, picture-wise?

The short answer is technically and most likely noticably NO.. it is not. All HDTV.. whether it be satellite or cable... is alot more compressed then video on a Blu-Ray (or HD-DVD) disc would be. So your more likely to see tiny picture abnormalities and compression artifacts on HD television. Also... I believe all HDTV does a maximum of resolution/spec of 1080i.... whereas Blu-Ray disc can do 1080p.

It is concievable some people may not notice a difference, however. Some people are just not that perceptive of visual differences in what they watch... whereas others will notice things right away. Also.. I suppose if you have a very small or a low end (720p) HDTV... the difference may not be noticable either... particularly if you sit farther from the screen. Essentially if the TV is scaling down to 720p.. the reduction in resolution of both HDTV and HDdisc video may negate much of any difference you would see.... although even then you might still see some small signs of compression artifacts (blockiness.. sporatic glitches.. etc).

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They actually can't "not compress at all " a HDTV broadcast. By the very nature of the technology it needs to be compressed. Sports games, however, can look very good on HDTV. Sports is always broadcasted in 720p I believe, as appose to 1080i.. because progressive is better for motion plus it CAN be compressed less then something in 1080i. So againa, particularly on a lower end 720p TV, you may not notice the difference as much, since your comparing 720p TVfootage and 1080p Disc footage downscaled to 720p.

It can also look sharper because when watching sports, everything is meant to be in focus and highly sharp looking. A movie however will have some things out of focus on purpose (like in the background etc) and may not look as distinctly sharp.

It depends on the feed they are sending at the time. When airing football games and late evening shows they dont compress at all and they use really good cameras, and it is, i kid you not, better than blue-ray. but if they are compressing the video as they often annoingly do, it will be grainy and not look as good. Still, they usualy send out a good HD picture.

I have both. The answer is clearly NO.

There is a noticably difference between the two. Mostly the clarity. Even the best feeds (CBS, NBC, USA, HBO, and Showtime) have a pretty noticable difference. It's not a HUGE difference but everyone can notice it (even my kids).