Bestseller and Smash hit

Bestseller noun - A book that has had a large and rapid sale.

Smash hit and bestseller are semantically related. in success topic. In some cases you can use "Smash hit" instead a noun "Bestseller", when it comes to topics like blockbuster. informal substitute

Smash hit noun - An unusually successful hit with widespread popularity and huge sales (especially a movie or play or recording or novel).

Bestseller and smash hit are semantically related. You can use "Bestseller" instead a noun phrase "Smash hit".