A book report is a paper written to discuss a specific book. Exactly what needs to be in that report will vary depending on what an instructor asks for. Some instructors want to see only a summary of the book and the main points the author made. Other instructors will want you to talk about how the book made you feel, or what you think about a particular aspect of the book.
A thesis is a piece of original research. It generally uses a lot of different books and articles as references. It's also possible to use movies, websites, videos, and personal interviews as references, too. When you write a thesis, you need to read what a many authors say on the subject you're writing about, and incorporate them into your thesis paper. Your instructor will generally tell you how many references to use.
