Byzantium, wrought with internal corruption and outside pressure from forces such as the Sassanids, Bulgarians, and Serbians could never maintain control over much outside of Greece proper, Asia minor, Thrace, the Macedonia region, Epirus, and perhaps a few scattered Islands, ports, and territories like the Ukraine, Sicily, or Malta. As a result you'd have other, more domestic, Orthodox christian countries stretching from Sinai to Cyrenaica, and a Islam dominated Levant.
You'd probably have a stronger Coptic Egypt that would have very strong trading ties with Greece due to linguistic and lexical similarities. Egypt would likely expand pretty far south to modern Khartoum. Axum would have strong trading ties too.
With Orthodox Christianity still a stable force by the time of the OTL Crusades, they may just not happen. OTL the Byzantine emperor called for the Pope's assistance in "Christian brotherhood" in order to collectively fight the rising power of Islam that threatened Constantinople. With an Orthodox north Africa and Balkans, even with an Islamic Levant nearby, Orthodoxy could fight off Islam without Catholic help. The Crusades may just be butterflied away.
Is North Africa isn't penetrable, Islam may just move further east too...If that's possible. Before Europe arrived in the 16th century, the Indian Ocean basin was in the hands of Islam, controlled by Safavids, Mughals, Arabs, Ottomans, and the like. It never would be able to penetrate China, but India may become more Islamic, especially in more traversed regions such as around the Ganges and Sri Lanka. I think an Islam that is more aggressive in the east would lead to confrontation with the major Buddhist power: China. Especially considering China and the Islamic world both are going for Central Asia in the long run.
So in short:
Catholic/Protestant world: West Europe, Central Europe, North Europe, Iberia, North Italy, Barbary coast, Tunis, Tripolitania
Orthodox World: Greece, Asia minor, South Italy, Sicily, Cyreneica, Egypt, Sinai, Armenia, Caucases, Assyria, Balkans, Malta, Russia, Axum, Horn of Africa
Islamic World: Arabia, Mesopotamia, Levant, Iranian Plateau, North-west India, Ganges Basin, Sri Lanka, India south of Jaipur, most of Sumatra, west Java, Horn of Africa, parts of Central Asia.
Buddhist world: China, Mongolia, Japan, Korea, Aceh, Riau, East Java, Indochina, Siam, the rest of the east India, parts of Central Asia, Burma, north-east India.
Hindu world: Muslim parts of India, Sumatra, and Java. It will be have heavily syncretized to the point where it is monotheistic and very similar to Islam, though perhaps more spiritual and passive.