The two distinct African culture groups are North Africa and sub-Saharan Africa. North Africa has been largely influenced by European cultures and Islam, and is considered part of the Arab world. Sub-Saharan African cultures are influenced by the harsh desert environment and years of isolation.
Sub-Saharan Africa is largely considered "black" Africa as the peoples inhabiting this area tend to have very dark skin. In North Africa, the lighter-skinned Berbers and Egyptians mixed with Arab people early in the area's history. The Sahara Desert kept sub-Saharan Africa from mingling as much with Eurasian people, so the traditional African cultures of tribalism and early folklore have continued to the present day.
North Africa is a mix of Islamic influence, European influence (especially French), and traditional African influences. Currently, North Africa is so heavily influenced by Islam and Arab culture that it is widely considered part of the Arab world. North Africa comprises Egypt, Algeria, Libya, Morocco, Sudan, Tunisia and the Western Sahara. Morocco is probably the most mixed of African cultures. Moors, Jews, South Africans and Arabs have all had influence on its culture and societal structure.
The country of Mauritania is an Islamic republic, but culturally, it is probably the least influenced by the Arab world of all North African countries.