Senegal is 17 times larger than Gambia.
Area: 11,295 km2 World Factbook
Population: 1,925,527 (July 2014) World Factbook
The Gambia is a country in West Africa. It is surrounded by Senegal, apart from a short strip of Atlantic coastline at its western end. It is the smallest country on mainland Africa. 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