what is the difference between macros and subrotines?

1.macro doesn't have any return statemen.but a subroutine
can have 
2.execution time needed for a macro is much lesser than
subroutine
3.memory requirement for a macro is generally heigher
4.subroutine can be classified as stated in Previous
answers..but no such classification is available with macro
although macro can have different types of nested form
5.generally no of instructions in macro are smaller than
subroutine
6.macro is always local to the program that defines it
subroutine may or may not be local.