https://stackoverrun.com/it/q/1633312
In quella pagina:
While Linux, and therefore also Android, normally is case-sensitive when it comes to filenames, FAT file systems, which are often used on SD cards, memory sticks etc., are case-insensitive. Therefore, Android will not differentiate between cases when it is handling files on these file systems.
So if you have two files, /sdcard/file (on the SD card) and /data/file (on the internal file system), you will get the following results:
new File("/sdcard/file").exists(); // true
new File("/sdcard/FILE").exists(); // true, /sdcard is a case-insensitive file system
new File("/data/file").exists(); // true
new File("/data/FILE").exists(); // false, /data is a case-sensitive file system