Area doesn't necessarily mean a bigger piece of land. Sure, an area can be split into 'zones' but an area can be the amount of space in a circle or other object in math. I think zones are more for outlining specific areas for certain purposes. Time zone, for example. An area, I think is more the general term for a place. I guess, I would area's more flexible (except in math). A zone is outlined. An area you can 'outline' however you'd like to. For example, the North Eastern States can be an area of the US (how do you define the North East? From NJ to ME, from PE to NY, from Mass to ME?). Whereas a zone would be a school district, a specific zone for a new building to be made, a time zone. These all have specific boundaries that can't be re-defined by others.