The experience of anxiety is exactly the same in both cases as it's an adrenal response, but the physical is triggered by hormonal imbalance and the psychological is triggered by anxious thoughts. So if it's purely hormonal, psychotherapy will not be of much help beyond stopping things spiralling further out of control.
In the same way that docs shouldn't throw pills at all types of anxiety, us therapists shouldn't assume it's all mind driven!
However, many people may not be aware of the subconscious thoughts behind their psychological anxiety and that's where a therapist can be of great help in working with you to discover the source.
In order to recognise the difference, if the anxiety hits at certain times of the day/month or when there was no obvious reason, like in the middle of watching TV, it's probably hormonal. As much as psychological anxiety can surprise us out of the blue, most would be aware of a situation triggering it even if they don't understand why.