It is the nature of the sensory question that decides which sensory method will be used to resolve it. Once we have received information about questions that need to be answered with the aid of sensory analyses, we will decide, in dialogue with the principal, which method would be technically correct.
Descriptive tests are the most comprehensive and give the most sensory information. Difference testing provides information about whether any difference can be registered between the samples, without giving any information about the character or intensity of any such difference.