What is the difference between a worry and an intrusive thoughts?

I'm now realise I don't really understand the difference. From my knowledge an intrusive thought is something completely against what I actually feel and something u dint want ti think about but I obsess over that it's actually real. So then what is a worry? Is a worry something that could be real and I obsess over. I feel like I obsess over both and I don't completely understand the difference.

I think the issue is is that my ocd convinces me everything could be a genuine thing that could possibly happen no matter how outlandish and unbelievable it is.

Any replies are appreciated! Thank you!