Voltage and potential difference are the same thing. Nobody out of school uses the latter term. Voltage is the potential in an electrical circuit to cause the flow of current (ie, electrons). wikipedia: Voltage is commonly used as a short name for electrical potential difference.
Population of Jamaica 2014. As of 1 January 2015, the population of Jamaica was estimated to be 2 767 704 people. This is an increase of 0.73 % (20 112 people) compared to population of 2 747 592 the year before. In 2014 the natural increase was positive, as the number of births exceeded the number of deaths by 34 785. Due to external migration, the population declined by 14 672. The sex ratio of the total population was 0.969 (969 males per 1 000 females) which is lower than global sex ratio.
Jamaica lies 140 km (90 mi) south of Cuba and 190 km (118 mi) west of Haiti. At its greatest extent, Jamaica is 235 km (146 mi) long, and its width varies between 34 and 84 km (21 and 52 mi). With an area of 10,911 km 2 (4,213 sq mi), Jamaica is the largest island of the Commonwealth Caribbean and the third largest of the Greater Antilles, after Cuba and Hispaniola. Many small islands are located along the south coast of Jamaica, such as the Port Royal Cays. Southwest of mainland Jamaica lies Pedro Bank, an area of shallow seas, with a number of cays (low islands or reefs), extending generally east to west for over 160 km (99 mi).