if you have never watched the Animatrix, I advise you go rent it. It has a history of how the matrix came to be. It will make it slightly easier.
They compare because one central dictorial government that the people give the power to. After that, the government begins to completely control the people. In the Matrix, it is subconcious, the machines take over. In 1984, it is out of fear, the Thought Police could come at any moment. Nothing they do in their lives is up to free will, they think they may have it at some times, but really there is no free will and the government is controlling everything that they do. When they do realize they have free will, and exercise it, they begin a war of their own against the government, doomed to fail with no ending in sight.