A little research....here ya go
Longfin Bannerfish = Heniochus acuminatus
The Longfin Bannerfish is recognised by the long tapering dorsal filament, white body with two broad black bands, and yellow soft dorsal and caudal fins.
Schooling Bannerfish = Heniochus diphreutes. It looks very similar, but is distinguished by a more rounded profile under the head, a shorter snout , the second black band is located further forward on the anal fin, and a difference in the number of dorsal spines (12 vs 11). This species grows to around 25cm and eats zooplankton and bottom-living invertebrates
Actually, their are 8 species in this Genera: Heniochus