I just get a different kind of feeling with an obsession to a casual interest. When I have an obsession, I want to find out everything I can about it, I write endless stories about it, I draw endless pictures of it, I will get into a bad mental state of I was to lose it, I think about it the majority of my time, and I don't know when to stop talking about it to close people.
With a casual interest, it's a little different. I don't keep thinking about it all day, and I only talk about it sometimes, like everybody does with their interests. I don't want to find out every single thing about it, and I don't write endless stories or draw endless pictures of it, maybe just the odd picture or odd story perhaps when I'm bored or something. It can make me feel good but I just don't get that obsessive feeling, and if I find out a new fact about it I don't always memorize it or I don't get excited.
That's how I experience the differences between the two.
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Female