"Do you think that an organization that is so exact, that sends material all over the world would call something by two different names in the same publication unless there was some difference. You tell me. I'm just asking."

It is entirely possible, as there is no official ruling on the proper step name by any committee, except for the syllabus figures. So two different authors within an organization could choose to use two different names.

But where did you get this idea about two different names in the same letter anyway? The original poster used one name, the letter you found used another. What is to be suprising about that?

You're going to have to learn to accept information from sources other than your holy, blessed pieces of paper... or you are going to be left in the dust by those willing to learn.