Every iPhone owner has seen the contradiction: iCloud says you have 5GB free, but Settings says storage is full. One is lying. Both, actually.
The Two Numbers That Don't Talk
iCloud (5GB free tier) measures your cloud allocation: backups, iCloud Photos, Messages, app data, and documents. It has nothing to do with how much space is left on your phone.
Local storage is the physical NAND on your device. It competes with apps, caches, system data, and your photo library. "System Data" alone can bloat to 20GB with zero explanation.
Apple designed these as separate systems and gave them similar-sounding names. The result: millions of users who think deleting photos frees iCloud space, or that buying more iCloud fixes a full phone.
