Texture atlas, or packed texture, same thing. The modeling style is called modular, ala the Mod Facade Challenge. More modularity info here: http://wiki.polycount.net/CategoryEnvironment
To be fair, English is probably not his first language. Cool time-lapse video here, showing modular building creation. All photo-source, but cool nonetheless. http://www.citiesxl.com/index.php?/content/view/1/32/lang,en/ I like that it's time-lapse, doesn't waste my time. Funny that many commenters thought it was…