@youdontknowwho
Hmm. Based on the website, they are supposed to be separate productions, although [3] and [4] could be the same thing. This is assuming that the website info is accurate, which may not be, since anyone seems to be able to edit the website. There's no source listed in the website as well. Personally, I'd want a more credible reference. Anyway...
[1] https://movie.douban.com/subject/35357255/
Fox Volant of the Snowy Mountain. The images show that it's affiliated with iQIYI (爱奇艺), an online video platform. It's listed as an upcoming movie (电影) with an existing trailer at iQIYI website.
https://www.iqiyi.com/lib/m_2541762759279514.html
[2] https://movie.douban.com/subject/30464358/
Fox Volant of the Snowy Mountain. The only image there shows that it's affiliated with iQIYI and Huace Group. The listed director is different from that of [1]. A Baidu Baike article says that it's going to be a TV series (电视剧).
https://baike.baidu.com/tashuo/browse/content?id=caaff993a2060088ab7394e7&lemmaId=17488175&fromLemmaModule=pcBottom
[3] https://movie.douban.com/subject/27121221/
The prequel, The Young Flying Fox. The director is listed as Lian Yiming, but the summary mentions Zhang Jizhong talking about how he originally wanted to flim Fox Volant, but he had to settle for the prequel because the right to do so was already taken by someone else. Why does it mention Zhang Jizhong if the director is Lian Yiming? This part is rather confusing.
[4] https://movie.douban.com/subject/27195127/
The prequel, The Young Flying Fox. The director is listed as Zhang Jizhong (张纪中), who is known for producing quite a few Jin Yong's stories. It doesn't even have a promotional poster/cover.