Jefferson Nickel Reverse of 38 vs 40 "Type" or "Variety"?

Intueor

Over the years, I have read several articles on Jefferson Nickel Reverse of 38 vs 40. I have a few of both respective year and reverses in my collection. The one thing that seems to be elusive is whether this difference in the reverse is a “Type” or a “Variety”. Put in simplest terms, it is my understanding that the primary characteristic that distinguishes a “Type” from a “Variety” is that "Types" are intentional but "Varieties" are accidental. A type, by design, is a premeditated alteration to the devices of a coin to modify the appearance of the coin. Types can be “Simultaneous”, within a single year and/or “Transitional”, spanning more than one year. So is the Jefferson Nickel Reverse of 38 vs 40 a “Type” or a “Variety”?