Usually when people talk about "larger", they mean population. If you are talking specifically about geographical area, sure, but it's usually explicitly named. If you compared the metro area of Mpls to Albuquerque, I bet it's way larger geographically as well. So really my point is that when someone says somewhere is a big city, they don't mean the central city, but rather the metro area. The population or geographical size of the central city has little to do with what it's like to live in or visit a metro area, in terms of cultural variety, economy, and so on.