These two are a bit different. In Quora, people can ask specific questions, and people can provide the needed answers. There are times when they may add some images to the items so that they will be easier to understand. In Reddit, people have the power to share all of the details that they want.
They can talk about the news if they're going to, and they can also share content that can be voted up or down by the other readers of Reddit. I am probably biased towards Quora mainly because I like the material better so if I were asked which one will be able to survive in the future, I would say Quora.