The difference is Fiction vs. Non-Fiction. Gravity was never meant to be historical, but they did take the effort to make the HST, STS, ISS, and the space suits look as realistic as they possibly could. Expect to be entertained, not a NASA history lesson, and you will enjoy this action packed movie.
No, the difference is between having a good
story line and not having one. Babylon 5
played fast and loose with the physics of space travel, but it had a very good story line that worked. Gravity
didn't. I could have thought of many ways to make that movie into something more than a typical space disaster movie (ala "Marooned"), elevating the main character into something more memorable. It didn't happen. The movie was OK, but just wasn't what I had hoped it would be because the story line was kind of weak. Clear skies to you.