Regardless of whether they call it a critique, a report, or a review, professors tend to want the same kinds of things when they ask for you to write about a book.
Most professors are skillful at determining whether a student has actually read the book.
On the other hand, the instant that a professor suspects that a student has not followed those two rules, the professor will be on the lookout for evidence to prove these suspicions. When you read a book, take notes about it and formulate your thoughts as you go along. Before you sit down at your computer to type your paper, review your notes. You should be able to write most of your critique without looking back at the book. If you continually are paging through the book, the result is likely to be a string of paraphrases taken from the book rather than your own evaluation.