There is a variant of Swimming Dragon called "Willow Waist" that I've only learned about because I showed some female qigong types swimming dragon and was told, "oh, who showed you willow waist?" And then when I asked about it, they wouldn't expand as they were two (perhaps subtly? I dunno) forms.
I've seen Swimming Dragon taught to men and women, but the aforementioned women I know who know Willow Waist, won't show it to men, so I couldn't tell you the difference.