Not sure why no one has touched on this, but the reason that blu-ray looks better than cable, sat, and online streaming is fairly simple - it has to do with compression. Blu-ray uses minimal compression to maximize video and audio quality, and can do this because a typical blu-ray disc (DL) can hold upwards of 50 gigs, which means they can deliver their content at a very high bit rate.
Cable, sat, and online streaming sites have to squeeze that content into a much smaller package (this is referred to as compression), and they do this for two reasons: 1. to be compatible with the relatively low internet speeds available across the country, and 2. (and this is the main reason) because it saves the ISP's a ton of money by not having to upgrade their infrastructure (servers, data lines, etc.) to be able to handle to increased bandwidth requirements. Hopefully, this clears up the confusion. :)
Cheers!
-David
Cable, sat, and online streaming sites have to squeeze that content into a much smaller package (this is referred to as compression), and they do this for two reasons: 1. to be compatible with the relatively low internet speeds available across the country, and 2. (and this is the main reason) because it saves the ISP's a ton of money by not having to upgrade their infrastructure (servers, data lines, etc.) to be able to handle to increased bandwidth requirements. Hopefully, this clears up the confusion. :)
Cheers!
-David