Yup - Dark matter is simply stuff we haven't seen yet. It might be tiny particles of types we don't understand, it might be supermassive black holes, it might be lots of small black holes, it might be lots of free-floating planets not around stars, or Jupiter-sized gas planets that weren't big enough to ignite into stars, it might be little rocks, it might be accounting errors. It might be weird stuff, it might be non-weird stuff. There's enough of whatever it is to have enough mass that galaxies act differently that we'd expect from the amount of matter we can see (i.e. mostly stars.)
Dark energy is a lot weirder. It's not defined as just the energy form of dark-matter-on particles, it's a different problem.