Internal Sales Order Accounting flow

Hi All,

We have internal sales orders process with in the operating unit and across operating unit.

we have multiple operating units say like US,MEXICO,GB2(Briton), CANADA, etc.. 

we are creating internal requsitions with in US and across US

case1: source organization and destination organization both are in US operating unit

case2: source organization is in Mexico and destination organization is  in US operating unit

Is ISO end to end functionality is same or is there any difference in the above 2 cases

as a project mate i dont have visibility beyond purchasing scheema.

so here iam clear about internal requisition creation, approval, ISO creation, releasing, shipping.