yes - there is a difference between delusional or reality-based thoughts/behaviour
When a person has a fear based on an aspect of reality - then that is not a delusion.
It's like - myself - I had fear of my mother; I feared that she might harm me; my fear was not delusional because she had assaulted me in the past (reality).
If nothing had ever happened before - then it could still just be fear (because there are a lot of dangers out there in the real world).