Difference Between Wuxia, Xianxia, and Xuanhuan

奇幻: Qihuan, 奇(intriguing, magical) 幻 (fiction), usually refer to novels that set in a western culture background. It usually has kings, noble, knight, magic, elf, dragons, and sometimes heaven, hell, angel, Demons and Gods. This type should be the most familiar type for westerns. Names in this type of book are western. Coiling Dragon is an example of this.

玄幻: Xuanhuan, 玄(abstruse, unreal) 幻 (fiction). This term is use for those fiction set in a eastern culture background(in contrast to 奇幻Qihuan). In Xuanhuan you get five basic element (metal, wood, water, fire and earth), Chinese style gods, powerful animal monster like fox and tiger who can transform to human look, Taoist practice that allow human to become immortal, etc. It's a really general type, and Xianxia is just a subclass of this type. Against The Gods and Martial God Asura are examples of this.

科幻: Kehuan, 科(science) 幻 (fiction). Science fiction, basically

Wuxia: literally means "martial hero", dealing with martial arts, sorcery, and chivalry.

Xianxia: Xianxia and Xuanhuan is commonly confused with one another, which is understandable. Xianxia is more focused on a key background setting that human can become immortal(仙xian) through Taoist (in most case) ways. There is another term almost equals to Xianxia called 修真, 修(practice) (to become) 真(true, immortal). ISSTH is an example of this.

A lot of people seem to know that "Xianxia" is "immortal hero" without understanding that what makes Xianxia is the "xia" part of it—which is hero. If the MC isn't generally a good guy, then it's not Xianxia. If it has a lot of the elements of Xianxia, but the MC isn't a good guy, then it's a Xiuzhen story.(ex. Xian Ni and Stellar Transformations) tl;dr Xianxia is a high fantasy story with a lot of Daoist elements and a good guy MC. If it none of that fits, then it's not Xianxia.

Xianxia is basically an umbrella term for westerners. Most of the novel we think are xianxia are not. ISSTH is a true Xianxia because the MC is a good person. Something like Xian Ni (where the MC isn't good) is not , but it has other Xianxia qualities and is thus a Xiuzhen.