USB sticks are traditionally formatted with FAT 32, because this file system is implemented by almost every operating system and device. Unfortunately, it sucks, as it cannot use more than 2 TiB, store files larger than 2 GiB or store symbolic links for instance. In a word, it is an obsolete and deficient file system.
Good news: someone addressed that problem. Bad new: that someone is Microsoft. So as you could expect, exFAT, the extended FAT, is a stinking proprietary, secret and patented file system. There are free implementations of that shit, but it is safer to stay away from it.