According the Henry J parts book, they are different. It doesn't show illustrations but it lists them as "Fan" part number 212888 four cylinder and 208929 six cylinder.
I've attached pictures of both of the engines from the front. Perhaps they reveal the difference. The picture dated 7/25/2001 is the four cylinder the other is the six. They look the same to me - perhaps the blades on the six a bit longer??
