Most times, we indicate the plant organ affected when describing a plant disease symptom. There are gradations from spots to blights and the better term to use may not always be clear. They are usually associated with the woody growth of stems and branches. Cankers, again, found mostly on stems and branches, are sunken lesions. Wilts occur when plants droop, indicating problems with water uptake.
Rots occur when tissue breaks down.
However, dry rots can occur. It is important that you get used to using these terms, so that everyone is on the same page when describing symptoms. Examine the following set of pictures.