What's the difference between `return;` and no return?

php code

<?php

function a() {
   echo 1;
   return;
}

function b() {
   echo 2;
}

generated bytecode

.FUNCTION a
        ECHO                     1
        RETURN                   NULL
        RETURN                   NULL
        HANDLE_EXCEPTION         
.END FUNCTION

.FUNCTION b
        ECHO                     2
        RETURN                   NULL
        HANDLE_EXCEPTION         
.END FUNCTION

so the explicit return statement generates one extra RETURN instruction. Otherwise there's no difference.

As far as I know there is no difference.

The empty return; is mainly there to break out from a if/else, while or for loop without returning anything.

Functionally there's no difference but it's always nice to have an obvious point of exit in a function (the return). Some schools of computer science hold tht all functions and methods should have precisely 1, and only 1, point of exit.

Should you need to add a return value in the future then there's an obvious point already picked out for you in the code if you include an empty return.

But like I said, from a functional point of view there's not much difference.