Winston's apartment is certainly drab, as it's basically just a bare, utilitarian living space designed to support the basic functions of life for its tenant. The room that Winston rents from Mr. Charrington is described as a bit more homely, as it’s a left over from an earlier, pre-Big Brother era, but it’s also described as “shabby” and very run-down. The rented apartment is not valuable to Winston for its opulence, but for what it lacks: a telescreen. A telescreen is not just a T.V. set, but also a camera designed to openly spy on its owners to create a sort of panopticon effect. When we first meet Winston, he thinks he has discovered one small corner of his apartment that is not under surveillance by the telescreen, but we later learn that this is not true. In Mr. Charrington’s back room, Winston can be certain that he is free from the eyes of Big Brother (he thinks):
It seemed to him that he knew exactly what it felt like to sit in a room like this, in an armchair beside an open fire with your feet in the fender and a kettle on the hob, utterly alone, utterly secure, with nobody watching you, no voice pursuing you, no sound except the singing of the kettle and the friendly ticking of the clock.
Of course, Winston discovers too late that Mr. Charrington’s room may not have a telescreen but it does have concealed surveillance equipment under Big Brother’s command, but this doesn’t negate the point that the difference in the apartments is that one (Mr. Charrington’s) offers Winston the illusion of privacy and security, while the other (his own) does not.