Why I can watch television on my laptop without an aerial?

But I can't watch television without an aerial? I've got a tv and even though I've got an internal aerial, the image is not very good and the image on my laptop is perfect, even though there is no aerial.

your laptop im assuming is newer. it has a digital receiver for the signal, and its internal and could possibly run through you internet connection, although unlikely. your tv has an analog signal receiver, so the connection is slower, and of a substantially lower grade.