Why identical-looking Galaxy phones can run different firmware versions

Two Galaxy phones with the same name can run different firmware because Samsung sells many hardware variants under one marketing name, each with its own model number. Firmware is built for a specific model number, so an update for one variant does not apply to another. Region-specific CSC codes and carrier approval steps also determine which update schedule a phone follows, so unlocked and carrier phones often receive updates at different times. Security patches and major feature updates are released in separate staged rollouts, so a gap of a few weeks between otherwise identical phones is normal. Checking the full model number and CSC under About phone is the first step in explaining a mismatch.