Doesn't seem to be what's going on here, or Akatsuki and Fubuki would be the same height.
No, not exactly. Akatsuki would actually be taller by a very slim margin. This is most likely just based on their apparent age as humanoid characters.
Edit: No wait, their lengths are listed in completely different ways on Wikipedia. I can't actually tell if their lengths are different at all.
On another note... Damn. Akatsuki and Hibiki are so alike that with their hair colour removed I was wondering why they used Hibiki instead of Akatsuki for this image. Of course, upon looking closer it's clearly Akatsuki's mannerism and her Kai Ni outfit, but they should have made her hair black, since it's dark blue and the dark parts of their outfits have been turned black.