D/s is a power dynamic where one partner (the Dominant) consensually maintains some level of power in certain areas over the other (the submissive).
M/s is a power dynamic where one partner (the Master/Mistress) consensually maintains a very high level of power in many or all areas over the other (the slave). It has a higher connotation with 24/7.
Neither of these relationship dynamics inherently connects to romance, sex, or kinky play.
A commonly heard idea in discussions about D/s vs. M/s comes down to when the choice to obey is made. Obedience in M/s is often seen as a one-time decision; the slave decides to obey when they become the slave of their M-type, and that decision is never really made again, because it’s already been decided. Obedience in D/s is often seen as more of an active decision each time the submissive follows their Dominant’s will, with each act of obedience seen as accompanied by a bit more of a thought process. Relatedly—internal enslavement is something I see referred to almost exclusively in M/s language.
D/s tends towards more negotiating than M/s, so a submissive might think about the implications of following an order more than a slave. If they do it now, does that set the expectation that they’re always okay with it, or that they’re okay with an escalation path going forth from it? A slave who gives up more control might not think of those things because they might not matter as much.
In those negotiations, it is more often seen in M/s that the slave does not have safewords, hard or soft limits, or the full ability to leave the relationship. It is rarer in D/s for the submissive to not have those things.
D/s is kind of a “headspace enforced” situation. If the submissive is not feeling like obeying at that moment, I see a lot of “then the headspace needs to be fixed” (often by the Dominant). M/s is more of a “headspace expected” situation, where the slave obeys whether they want to or not, and if they don’t want to in that moment, it’s not viewed as a problem; there’s just the expectation that they still want to obey overall, and their headspace will reflect that better later, in a likely fairly natural way.
Often, in fact, I think that these expectations are good for the desired headspaces in themselves, and the expectations for a submissive might be actively detrimental for a slave, and vice versa. A slave would feel discouraged if their M-type wanted to fix their headspace every time they internally didn’t want to do something; a submissive would feel discouraged if they didn’t get help with their headspace at the same moments. Same for how they feel they should address it within themselves.
The positives of being a submissive are often described as “the joy of the feeling of surrender”. It is associated with something you actively feel. The positives of being a slave are often described as “the joy of serving and pleasing another”. It is associated more with how you make your M-type feel.
With this difference in mindset, D/s often has the submissive’s headspace kept in mind when coming up with specific ways for the submissive to submit, with the submissive’s wanting to do those things being important. M/s more often has the Master/Mistress’ wants being kept in mind when coming up with specific ways for the slave to submit, and their desire to submit overall being the important factor.
I am frequently asked about my thoughts on this subject, and I wanted to create one reference on it; so, here it is.