Télévision vs. téléviseur
In French, 'télévision' and 'téléviseur' both relate to the concept of TV but are used in different contexts.
Télévision
'Télévision' refers to the system or technology of transmitting moving images with sound over a distance, as well as the industry and art form associated with this technology. It may also refer to the content viewed through this medium.
J'aime regarder la télévision le soir.
(I like watching television in the evening.)
La télévision française produit de nombreuses émissions intéressantes.
(French television produces many interesting shows.)
Téléviseur
'Téléviseur' refers specifically to the electronic device used to watch television broadcasts. It refers to the physical object rather than the service or content.
Mon grand-père a acheté un nouveau téléviseur.
(My grandfather bought a new TV.)
Le téléviseur est en panne, donc nous ne pouvons pas regarder le film.
(The TV is broken, so we can't watch the movie.)
Summary
While 'télévision' encompasses the concept of television as a system, service or content, 'téléviseur' refers precisely to the electronic device through which television content is received and displayed.