the difference between earth and terra

(noob question) whats the difference between the maps terra and earth?
as i dont quite understand the ingame explanation thanks

Terra: Similar to Earth in real life as in, the way the continents are generated, like we have Europa, Asia, Africa, the Americas, and so on.
Earth: Planet Earth in real life. Accurate protrayal or at least close to, of all continents. (albeit very small and you spawn randomly with either civ).

Terra : you and AI spawn on the main continents (Asia, Europe, Africa). Nobody starts on the new continents (America).
Earth : Everybody spawn anywhere.