North America, South America and Africa are the continent of the world. These three continents are very far from Nepal. They are different from one another in many ways. When it is a day in America, it is night in Nepal.
The USA and Canada have developed countries of North America. Nepal has a good diplomatic relationship with the USA and Canada. Many Nepalese students study in the USA and Canada.
North America and South America are alike in size as both are in triangular shape. Like the Rockies in North America, south America has The Andes. They both are stretched from north to south. Both continents have plateaus in the east and the central parts are plain.
North America is in the northern hemisphere and south America is in the southern hemisphere. The Rockies, the Andes and the Himalayas are young fold mountains. The Atlas of Africa is also a young fold mountain. Nepal is not so familiar with Africa. Countries of Africa came to highlight when King Gyanendra made a personal tour of African countries. It is hoped that Egypt will set up its embassy.
Among the continent mentioned in the questions, the Andes South America has similar physical environment to the Himalayas of Nepal with respect to height. Similarly, the western cordilleras of the North America and the Himalayas in Nepal share many things in common. In the same way, America and Drakensberg of Africa have some things similar to the hilly region of Nepal. In addition to these, the central low lands of north and South America have little similarity with the Terai of Nepal. Above, all the national parks of western cordilleras of North America and the national parks of Kenya and Tanzania have some similarities with the national parks of Himalayan region and Terai region of Nepal.
The principle occupation of the people of Africa is agriculture. They practice subsistence agriculture. Very few people engage in other occupations (about25%). Therefore, agriculture doesn't have alternative. Similarly, about 67% people in Nepal are engaged in agriculture. It is the compulsion of Nepalese people. On the other hand Canada and USA have created various sources of employment followed by industry and mining. Therefore, only 3% people work in agriculture.People of USA and Canada also use high-end technology in agriculture due to which manpower need is decreased drastically.