That they are two massively different occupations, with different goals, different processes and different regulations they fall under. Just about the only thing they have the same is low salary.
The point is that there's more overlap than how it looks like on the surface level. E.g. part of what a A.D. 1500 village pastor does is what's done nowadays by psychotherapists and marriage counselors; the role in filling the people's needs is similar even if the processes and regulations are wildly different, just as the processes and regulations of A.D. 1500 shoemaker or surgeon are wildly different than the modern shoe factory worker or surgeon.
