Why was What are the differences between détournement and deconstruction? closed? I added an opening sentence to repeat the title.
A good answer to your question would address the specific issues you're having in differentiating the two concepts. (Otherwise, one could just give you definitions, but you already have that in the passages you cite.) In order to do that, we need to know what those specific issues are: What makes it difficult for you to tell the concepts apart? What is it that makes you think they might have similar meanings? And so on. Your question would be a a lot clearer and if you included such explanations.
Also, your question would be better without the huge blocks of cited text. It makes it more difficult to focus your question, and places unnecessary burden on your readers. Instead just quote the crucial parts - for example, those that contain the definition of the terms.
I voted to close. The question was unclear, but I saw too many questions coming from you in one day. That may have had some influence. It is best to post no more than one question per day. This gives you more opportunity to win badges and incorporate any feedback you may receive.
Think about what it means to have a question closed. All it takes is five people clicking on the "close" button. These people are much like you. They might be having a bad day. They might not know anything about the topic and find it useless. They might not like the topic. Don't assume these people know what they're doing. Don't assume they are professional philosophers. I'm not one, but I enjoy the question-answer format of these sites.
What should you do if you get a question closed?
Use that as feedback for the next question. Also read questions and answers that have already been posted under tags you enjoy. This helps you get a feel for what questions survived being closed. Ask yourself what you could learn from them to write your next question. Up-vote the questions and answers you found useful. Maybe even answer one if you can reference your answer adequately. Try again. Think of it as a game that helps you learn something interesting as you play it.
As far as the topic of postmodernism goes, you may be the expert on that topic among the currently active users here. I am certainly no expert on postmodernism. If you want to promote postmodernism become the expert others learn to trust.