What if the Visigothic Empire and Byzantine Empire had reversed fates from the 700s on?
The Visigoths repel the Umayyad invasion, surviving for centuries, sometimes expanding and sometimes declining until an ultimate fall. Afterward an Ottoman-like empire (but Berber) takes over and rules al-Andalus.
On the other hand, the Byzantines are taken out in one war by the Umayyads, but successor states in the mountains of Greece launch a Reconquista of Greece, Thrace, and Anatolia. This takes centuries, but ultimately leads to several stable kingdoms. These kingdoms unite into a "Spain" (Thrace and Anatolia) and a "Portugal" (Greece).