Rotary rotary = Rotary(2, 3);
Is a lot like:
int Int = (int)3;
Except that "int" is a built-in type, while "Rotary" is a library-defined type ("Class" - more than a type, but quite similar.)
Since C++ is case-sensitive, "Rotary" (defined by the library) and "rotary" is just a user-provided variable name that could be anything.