A generic way to ask is just "Are they the same?" or "Are they the same thing?" Your two examples are kind of unusual though. You would be able to tell if two books are the same by the title, and you wouldn't like a book unless you had read it. Additionally correct ways to write your questions would be as follows: - I like this book and that book. Are they the same book with difference cover? ------> I like this book and that one. Are they the same book with different covers? - I like these two car. I think they are same model with difference color. Are they the same model? ------> I like these two cars. I think they are the same model in different colors. Is that true? Generally speaking you should not repeat the same sentence in question form-- it just sounds strange. A few other examples of asking if things are the same: -- Are these shirts the same size? -- Are we talking about the same person? -- Is he going to the same place? Etc.

Is the blue book the same as the red book? How is the blue book different from the red book? What's the difference between these two books? How are are these two books the same?