Q: Asalamualikum, In ref to 16:103, does this mean that Mohammad (SAW) spoke a different language/dilect than the Arabic form in which the Quran was revealed?
A: Walaikumsalam,
Rasoolﷺ and the Quraysh both spoke Arabic and the Quran was revealed in Arabic as well. However, Quranic Arabic was revealed in Fusha (Classical Arabic)—a refined, eloquent and inimitable linguistic form that was was not part of everyday dialects spoken by the Arabs, including the Quraysh.
While the dialect of the Quran may appear to be Qurayshi, its dialectical perfection, grammatical structure, literary style and depth of expression were far superior to that of common speech. This is why the Quran and Hadith often sound different. Hadith reflects the Prophet ﷺ’s spoken language, whereas the Quran is Divine speech. Some Hadith, like Hadith Qudsi also contain revealed words from Allah (SWT) but are distinct from the Quran in authority and style.
A useful comparison would be Queen’s English versus conversational English—both belong to the same language but differ in formality, precision and literary quality. The key difference, however, is that the Quran’s distinction is not human-made; it is Divinely inspired, making the gap between it and ordinary speech far greater than human linguistic comparison.

Allah Certainly Knows Best.