Google Maps is vector based. Are you perhaps talking about the original "Maps" app on iOS 5 (and below) which relied on Google data? On Android, you can select

Google Maps is vector based. Are you perhaps talking about the original "Maps" app on iOS 5 (and below) which relied on Google data? On Android, you can select regions of the map to save for offline use and the file sizes for entire cities are only a few MB. I don't believe a "save for offline use" option is available for Google Maps for iOS yet.