What is the difference between political South America and geographical South America?

Geographically, the continent of South America includes the territory from the Panama Channel in the north, the Caribbean shoreline - including the ABC islands, up to the north eastern tip of Trinidad, to the Cape Horn in the south. That would include the continental territory of the nine Spanish speaking countries Chile, Argentine, Uruguay, Paraguay, Bolivia, Peru, Ecuador, Colombia and Venezuela. The southern part of Panama. The bigger part of Trinidad and Tobago: Trinidad, Brasil, the French overseas territory Cayenne (or French Guyana), Suriname and Guyana. But the Unasur (Union of Southamerica) consisted of Brasil and the nine Spanish speaking countries, including offshore islands like Fernando do Noronha (Brasil ) Easter Island (Chile) Galapagos (Ecuador) and a number of Islands in the Caribbean, belonging to Venezuela or Colombia. The rest was considered part of Caribbean or Central America. Only lately the two countries Guyana and Suriname have joined the Unasur (Leaving the loose formation of Caribbean countries) French Guyana considers itself part of Europe. The ABC Islands still keep a depending state to Netherlands.