In Terms .NET 3.5, What is the difference between an executable assembly and a class library?

An executable assembly exists as the .exe file while a class library
exists as the .dll file. Executable assembly represent executable
applications having some entry (e.g., Main() method in C#). A class
library, on the other hand, contains components and libraries to be
used inside various applications. A Class library can not be executed
and thus it does not have any entry point.