Yeah it's the same thing, a service dom has different levels but generally is focused on caring for their partner. Pampering and focusing on making them feel good. They tend to be the lead in the relationship and thus have the 'dominant' role, but do so in a unique way that is more typically expected of a sub. It's one of my favorite dynamics in stories, just really hard to ever find.
A bit mature example...
An example might be tying up the sub and focusing on pleasing them (usually without having any sort of S&M but that can sometimes be present) and not letting them go until they're totally spent. The focus is always on pleasing their sub. So the D/S aspect is that the sub doesn't get to control the scene (outside of safe words and the like) but is still at the whim of their partner, but they aren't usually ever made to do anything. They get to lay back and enjoy the ride.