The meaning is the same, with only a very slight shade of difference. The difference is where you would use each word and what people you would use each word with (formality). Usually you will find the word "Reserved" on a table in a bar or restaurant instead of "booked," and I would argue that "reserve" is more formal than "book," but it's also less definite. For example, I recently booked a flight with a discount online travel agency, and they made a reservation for me with an airline. When I called the airline to check about the flight, they said I had a reservation, but I did not have a ticket, because the airline and the agency hadn't agreed on the price yet. So, I had a reservation, but my flight was not booked, because I didn't have a ticket! Language in use: Andre the Traveler and Betty the Hotel Clerk A: I'd like to make a reservation at your hotel, please. B: I'd love to place your reservation, but we're all booked up. (We don't have any more space) A: How long are you booked for? B: It looks like every room has been reserved until Monday. A: Can I reserve something in case someone cancels? B: I can't do that personally anymore with the new computer system. You'll have to check the website and book a room online if you want to do that.

reserve = book

"reserve" is a more general purpose word that I would recommend using most of the time. "book" is used in special cases (e.g. booking a flight, as mentioned by Brandon.)