Nigeria is 4.7 times larger than Senegal.
Area: 923,768 km2 World Factbook
Population: 177,155,754 (July 2014) World Factbook
Nigeria, officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. Wikipedia
Area: 196,722 km2 World Factbook
Population: 13,635,927 (July 2014) World Factbook
Senegal, officially the Republic of Senegal, is a country in West Africa. It is the westernmost country in the mainland of the Old World or Eurafrasia and owes its name to the Sénégal River that borders it to the east and north. Wikipedia