How is the current government different from any previous governments in 1984? What invention enables it to be like this?

The government of Oceania differs from prior governments in that it is able to keep its citizens under constant surveillance due to the invention of the two-way telescreen. Through the telescreens, Party members can be watched and recorded 24 hours a day. They can even be addressed, as when Winston is scolded for doing his exercises poorly. They are subjected as well to incessant propaganda from the screens.

At the beginning of the novel, Winston takes advantage of a tiny alcove in his apartment to get out of view of the telescreen, because normal Party members are never allowed to turn the telescreens off. In fact, Julia and Winston are utterly astonished when O'Brien can do so in his apartment: it is a privilege they can hardly imagine. Even in the proles' territory, versions of the telescreen intrude. For instance, although they think they have privacy in their room above Mr. Charrington's shop, Julia and Winston are being observed and taped from behind a picture on the wall.

This constant surveillance (or the threat of it) forces people to regulate their private behavior to such an extent that they have, in essence, no private lives.