Zambia is 2.2 times larger than Congo.
Area: 342,000 km2 World Factbook
Population: 4,662,446 (July 2014) World Factbook
The Republic of the Congo, also known as Congo or Congo-Brazzaville, is a country located in Central Africa. It is bordered by Gabon, Cameroon, the Central African Republic, the Democratic Republic of the Congo and the Angolan exclave of Cabinda. Wikipedia
Area: 752,618 km2 World Factbook
Population: 14,638,505 (July 2014) World Factbook
The Republic of Zambia is a landlocked country in Southern Africa, neighboring the Democratic Republic of the Congo to the north, Tanzania to the north-east, Malawi to the east, Mozambique, Zimbabwe, Botswana and Namibia to the south, and Angola to the west. Wikipedia