Heniochus diphreutes, schooling bannerfish

[super7]

I thought that there were differneces between the anal fins on each fish and that H.acuminatus has a more rounded chest. I do have a reef tank so I don't want H.acuminatus and want to make sure that I get the right fish. I'm guessing both species live in the same area, does anyone else know any tricks to distinguish between these two species?
Thanks Super7