>>213516061>>213516235Resolution is just the number of pixels available, but if it's a low-bitrate stream, it'll be heavily compressed and can still look bad.
Even with a blu-ray disc, there are some blu-rays that look relatively muddy and some that look amazing and clear down to the grain, depending on how good a job the company did with scanning the film and encoding it onto the disc.
Even the worst blu-ray looks better than DVD, though, which just doesn't have the canvas available to be able to display things with high detail