Mande means Manden. Manden is the name of homeland of a specific people. Manden is shortened to Mande, to identify the people. When you translate Manden into either Fulani or Arabic it means "Mali."
So when you say that a person is Mande then you are saying that they are from Mali or in Oprah's case her ancestors are from Mali. So she is from Mali.
Abu Bakr was Mandingo. Mandingo just means Mande+ngo (or Mandi +ngo). That "ngo" means "people of" or "subjects of" or "citizens of" Manden or Mali. Malinke means the same thing (Mali +nke). It just tells those people are from Mali, except Mande people are spread out all over West Africa now and many were brought as slaves to the USA and into other ares of the Caribbean and South America.
Other Manden tribes or ethnic groups are Mende, Boko, Vai, Susu, Soninke, Malike, Mandingo, Bambara, Bissa, Dogon, Kpelle, Maraka/Marka, etc., etc. They controlled trade over the entirety of West Africa at some point and their Mansas (Kings) became fabulously rich (Mansa Musa). In fact Musa came to the throne after Abu Bakr left to see what was on the other side of the ocean. Their story is very well known, which is where the story of the "Lion King" comes from. That is based upon the which the story of Sudiata Keita.
Many groups of Mande started rolling out of Mali at some point. "All of their stories starts the same. They were in Mali chilling and then some shyt went down, so they left." Most of it was just internal strife, but in many cases they settled along the trade routes that the Dyula and Yarse (traders) built across West Africa.