The differences between the Neo-Assyrian and neo- Babylonian dialects as manifested by the Royal letters in the Neo-Assyrian Period are slight differences which were divided into ordinary, phonic. Similarly there are some differences in the structure of nouns, verbs and text content. It is deduced that there are great similarities between the two dialects and that the phonic differences can help us to discover the dialect of the scribe whether Assyrian or Babylonian as well as a number of morphological structures of verbs like the subjunctive mood which must be observed carefully since there are certain Babylonian scribes who were skillful in using the Assyrian dialect in addressing the Assyrian kings.