Corpses, no, not really. There's an echo of who they were, but it's not them. I once called on a Roman legion, but I couldn't command them because I'm not Roman, and I hold no rank. So they were aware of that much. But in the end, they were still just soulless bodies doing what they were told. Tools.
Ghosts, though. They're different. The soul and body, it separates. The body is just a shell. But everything you are, that's the soul, and that lives on. [Maybe "live" is the wrong word. But he spends most of his time with the dead. He has guided and spoken to and even befriended those who have passed. Under the right circumstances, he could even bring the dead back to life.]