The biggest differences in most modern American made V8 motors is where number one cylinder is located, driver side front or passenger side front
That and a lot of other small things
Ford has had their firing order different since day one due to them numbering the passenger side from #1 to #4 and the driver side from #5 to #8 on the driver side instead of having the even cylinders numbered on one side with the odd # cylinders on the other side, Pontiac having a really weird one with the #1 being on the passenger side front of the block