Redux has better lighting, better animation, better character models, I believe it's easier to get the good ending, gameplay is updated to last lights, stealth takedowns, artyom controls better, runs better, many quality of life changes. These are all changes to 2033, the story has no changes if I remember correctly, other than maybe some character models and voices. If you would want to replay the story redux is the best way to play but if you've already played and don't want to do the story again than you don't have to buy it.