Global URL and local URL for invoking rest service in Business console gadget

while invoking external rest service from busniness console gadget(while drag and drop RAD to view or uploading swagger file into rest connector wizard), it is showing option to use either global URL or local URL to invoke rest service.
when I choose local URL option, swagger URL over written with auto generated url in RAD. can any body explain how gadget is using url in swagger and where can i see that configurations in gadaget