Fuji had several very minor tweaks on this focal length lens which can indeed be confusing from a brochure standpoint, especially since the lens labeling itself does not necessarily coincide with that. Inside versus outside of the barrel labeling has already been pointed out, and often hints at single versus multi coating. I just wanted one with a 52mm thread, so that's what I specifically bought. It is seemingly one of their more recent ones. I'm aware of four different filter thread options. The very latest version, the CMW, has a ridiculously oversized funnel front accepting 67 mm filters.
I wouldn't make too much fuss over any of these distinctions, and would be more concerned with only general condition if heavily used, including the condition of the shutter. Any of them should be excellent performers, optically.