Bill is fearful of most social situations, whereas andreas is only fearful of giving speeches. given this, one could infer that

It could be interfered that Andrea is likely to have less impairment than Bill as her fears only trigger in one factor in which are the action of giving speeches, where in Bill has fears of most social situations which could affect his entire life for his fear trigger often. That is why Andrea has less impairment compared to Bill who has more than her.