Cats and dogs can both view tv screens & monitors ... though their viewing experience is a little different to ours thanks to differences in cone structure leaving them color blind and giving low acuity.
Both species have lower levels of color vision than humans. Cats see slightly more color (in the blue green and yellow end of the spectrum) than dogs do so they may get more of an immersive experience from watching TV.
Further, cats and dogs need a higher frame rate than humans to make it appear as a smooth film, a phenomenon known as flicker fusion, in humans we require 15-20 frames per second, dogs require 70fps and cats about 100. Before the frame rate of televisions increased in recent years it would appeared to them to be flashing images, similar to when you point a digital camera at a screen which may explain why the dog is not interested in the TV, it'd be like staring at a strobe for hours on end. Here is a paper which discusses flicker rates and color vision in dogs.
To summarize there are several factors which influence the "enjoyment" an animal can take from watching a TV - their response to TV imagery will depend on the frames per second, colors, contrast, clarity, movement, subject matter, and (perhaps most importantly in my opinion) the temperament of the animal, for all of which there are difference between the species.
"We humans need about 16 to 20 images a second to perceive what we see
as continuous film, whereas dogs need about 70 images per second.
So a few years ago, Fido was probably confounded by his master's
behaviour of sitting for hours staring at a flashing succession of
images. With modern resolution and quicker imaging, dogs have become
potential television viewers.
This has not gone unrecognised in the USA, for example, where hopeful
TV producers have started special TV channels for dogs.
If you have other pets, however, you need to think twice before
placing them in front of the TV.
Birds need at least 100 frames per second to see TV images as a moving
picture. Having a bird in the same room as a TV with a lower frame
rate than that will be very stressful for the creature."