There are basically two types of paranoia, delusional and typical. Typical paranoia is you may think or wonder if people are talking about you, or out to get you, possibly your phone is tapped, your being followed, your being watched, people are laughing at you. Delusional is a bit more. Delusional is your convinced people are out to get you, your being followed, etc. I was once convinced my whole family and all my friends were in on a conspiracy to kill me! It was frightening, because you really believe it, not just wonder, you know it's true! Extreme cases of paranoia are the FBI or Gov is trying to kill you. Delusional is a break from reality, you totally believe the illusion in your mind to be true. There is no wondering.

I have been convinced at times the radio was sending me messages from God to warn me of a immanent attack from satan (I'm agnostic usually). I could smell death and even hallucinate demons. Hear voices warning me and threatening me. Convinced everyone in the world was out to get me. Another big difference is if it's actually possible, it's not really delusional, it's more on the line of anxiety and worry and wonder. At least that's how it's been explained to me.