How did taking the name of an ancient empire differ from Ghana?

Ghana was not named after an ancient empire. The ancient Ghana Empire existed from the 8th to 13th centuries in what is now present-day southeastern Mauritania and western Mali, and was named after the Soninke people who founded it. The modern Republic of Ghana was formerly known as the Gold Coast and was named after the ancient Ghana Empire by Kwame Nkrumah, the first President of Ghana, to symbolise the country's connection to its historical roots and as a source of inspiration for the country's development and progress.