They usually never bring both in the same template if one of them is the answer, as the lesion could appear quite similar. If they do, they would be fair and give you more details, like mention something about immunochemistry in the additional information. However, over the years they have been clear on this. Knowing the details might "assist" you in coming to a conclusion and finalizing your answer, but cannot be the base for diagnosing. That being said, ALWAYS pay attention to medical history in general, sometimes you need to read between the lines. It is also true that lesions confined to the gingiva only are more likely to be pemphigoid, but that does not exclude pemphigus at all. That is why they usually will not confuse you on this