Mobile memory, professional cards and all other standard cards

[32gb-sdcard]

How is possible that 32 GB SD card [Sandisk Ultra - micro SD U1 - HC I - class 10 A1] has higher cappacity than 32 GB USB drive [Sandisk Ultra Fit USB 3.1 Flash Drive]. About 1.2 GB diffrence. Both products are brand new, and formated to FAT 32