here where I am fantasies means the same thing as the word daydreaming. ... making up stories in our heads just because of being bored, nothing to do or to escape life at the moment...

example right now I am sitting at a computer. I can if I wish to and purposely want to I can start thinking up a story because I know its cold outside and I want winter to be over.

my daydream may start by noticing the weather and thinking wouldnt it be nice if maybe I am on an exotic island, drinking Pina Colada's while watching the surf roll in and out. then continue to build this thought of a warmer place into this big or small daydream.

intrusive thoughts on the other hand here where these odd bothersome thoughts pop in to my head, interfering with what i am trying to do...

example right now I am sitting at a computer answering this post but suddenly my mind throws a wrench in.. a thought about an abuse situation I went through that I got reminded of the other day. or Im sitting here at the computer having a good time playing cards and suddenly my mind throws in the wrench of an argument that I had last week. Im cleaning my house and suddenly my mind throws in the wrench of the time I broke my arm by jumping out of a tree. Im at work and suddenly my mind throws in the wrench of the thought about did I buy milk last night....

intrusive thoughts just happen any time of day and with out planning or meaning to, they just jump right into my day interrupting things. no story lines, no choosing for it to happen just bam theres that thought.