Question

Different between open subroutine and close subroutine

Answer 1

In case of an open subroutine, it is like a macro call, where the contents of the subroutine replace the call to the subroutine. Similar to the (inline) function call in case of C and C++.

In case of a closed subroutine, there is only one part of code, and a call to the subroutine results in a jump to the memory location where the code is placed. Similar to ordinary functions and subroutines in C and C++.