Are Answers.com and WikiAnswers the same?

No, WikiAnswers is not a rip off of Yahoo! Answers. Yahoo! Answers is a completely different site from WikiAnswers.

Yahoo! Answers is a site where individuals write an answer to a question, and the best answer gets voted upon and will be displayed as the best answer. The answer is as-is, and cannot be added to or have content removed from it, and once it has been answered, it has been answered and content can no longer be added or removed to and from a question.

WikiAnswers is a site where individuals add and remove content to an answer until the question is perfect. Any one can edit any one else's answers so that the answer can eventually be one, perfect answer. Answers will only be stopped from adding and removing content if the answer to a question has become more of an argument than an answer, mostly because the questions are asking for opinions. The answer is written over and over until it is perfect, and no voting occurs. Even unregistered users can participate by answering questions.

In short: WikiAnswers allows everyone and anyone to contribute to a single answer to a question until it is perfect, and questions will pretty much always remain open for editing, while Yahoo! Answers has individually comprised answers, where the answers are as-is, and will be voted, sometimes unfairly, for the best answer, which isn't always the best, and nothing can be added to it.