There's a different sizing under the freehub body for the two different bearing types ('standard' ball race and needle bearing), which is where the difference lies. And the end caps are different too as there's a circlip inside the freehub on the needle bearing version (EVO) which prevents 'standard' end caps from fitting. They may even be a different bore too.
As Matt says, Hope haven't got a f**king clue with stuff like this. You really struggle to find anyone on the phone who can help with anything mildly technical any more, it's really frustrating. The amount of times we've done exactly as Hope suggested to Dave and we've got stuff sent incorrectly is baffling...