Jianghu/kangho: the most generalised answer is “The part of the world the imperial court doesn’t have direct jurisdiction over.” You are talking about brothels, gangs, bandits, slums, the underworld, rogue disciples from various sects and more. There's no order and rife with crime. It's like taobao, lol.
Wulin/murim: refers to specifically and only to martial arts schools/sects/cults etc. The wulin is considered the refined, respected and virtuous people in society; they're also placed higher on the hierarchy. There's order.
If jianghu is taobao, Wulin is Tmall.