Why an App’s Download Size and Installed Size Can Be Different
An app store might show an app as a 200 MB download, yet the app can occupy considerably more space after you install and use it. The reverse can also happen: two people can download the same app and receive different amounts of data. These numbers are not necessarily contradictory. Download size measures data transferred to obtain the app, while installed size measures storage used by the app on the device. They describe different stages of the same process, and modern app delivery can make the relationship between them less obvious.