A reply paper responds to the concepts provided by presenting counter-arguments, etc. A critique is advice on how to improve the presentation of your thoughts. It does not have to be followed but it can help in finding better ways to express yourself. Reactions are responses that focus on whether or not you like something. They can be positive or negative. Critiques are opinions that discuss different aspects of a topic. For example, if I were to write a reaction paper about Harry Potter then I would say things such as "I hate Harry Potter" or "I love Harry Potter". But if I were to write a critique paper about Harry Potter then I might say things such as "Harry Potter movies are popular because of the action scenes" or "Harry Potter books are good because J.K. Rowling is talented at creating characters who develop over time". Both reactions and critiques can be formal or informal. Formal reactions and critiques are those that are written up according to a particular format or guideline. Informal reactions and critiques are those that do not follow this format; they can be unstructured papers or even just comments made in conversation.