What's the difference?

You seem to be contradicting yourself. If EGR came out in 74, then "EGR ports" in 73 would STILL have been "EGR," and furthermore, the diagram I posted was 72

It might well be that Cal eee foooornia had EGR before the U.S.

No, not at all. The EGR VALVE came out in 74. In 73 there were the EGR jets like you describe.