It's become more separate through kink associations, cuckold is about the wife doing what she wants and the husband being more submissive and giving into whatever his wife and her bull want from him. This includes clean up, Chastity, degredation, and even gay submission.
Hotwife/vixen/stag, is about a couple who are equals in their relationship but where the woman is allowed extra martial adventures with consent from the husband. The husband however is not interested in sex with other women or in being submissive to her bull. He wants his wife because he knows how amazing she is, but he also knows it wouldn't be fair to hoard someone that amazing all to himself.
Slutwife is the third dynamic I've seen played out in this lifestyle where the wife is submissive to both the husband and bulls, the husband picks who fucks her and where and when, she's basically a toy for his amusement and whoever he chooses to let play with her.
Swingers are a couple looking for a couple or third to play with together in a typically vanilla straight forward sex atmosphere with no Dom sub dynamic and no dis-inclusion of either the husband or wife from play