I've played with Hot Wife couples. It is its own part of the sexual world, more different from what most folks here define as swinging/lifestyle from a psychological perspective than behavioral. From the latter perspective most HW play resembles what people here think of as an MFM. But mentally it's all about the husband's enjoyment in observing his wife having sex with other men. (And in a healthy HW relationship the wife not only enjoying the sex for its own sake, it also for the erotic value it brings her husband.) The husband may at some point join in the play, but often not. Or at least not until the other male departs, when they engage in reclamation sex.
The Cuckold sexual lifestyle is a variant of the broader Hot Wife scene. As others have pointed out, it involves at least some level of humiliation of the husband, sometimes ea by the wife or the male (who the Cuckold world is generally referred to as a Bull) or both. In addition to the verbal "abuse" heaped on the husband, he is often "required" to fluff the Bull before he fucks the wife, and then clean them both up orally following.
From the perspective of many of the people who frequent the Swingers Board, the whole HW scene as a form of kink. (The Cuckold scene looks pretty kinky to me.) But then I think that most of my vanilla friends would find my sexual life to be on the kinky side. For sure my loving wife does...) So, I make a point of not judging.
For people who are interested in checking out the whole expanse of the HW scene I recommend the Hot Wife Forum: Our Hotwives - Index page