I know a ghost and a demon are different. I must've said that but I didn't really mean it. But right when I saw it, it smiled in a weird way that it might've had a plan like it had a big smile and it's eyebrows were down. Then I followed it but it ran away and disappeared.

Well, they are different in folklore... however I believe they are one and the same spirit. Which is probably why a lot of "ghosts" have that smirk... they know a lot more than you think they do.