What is the difference between FAT and FAT32?
First of, realize that FAT32 is a type of FAT. Not all FAT is FAT32,
but all FAT32 is FAT.
FAT comes in three "flavors"--FAT12, FAT16, and FAT32. The numbers
refer to the number of bits used in their addressing scheme. More bits
mean that higher addresses, and therefore larger drives, can be
addressed and accessed.
FAT12 was used only for very small drives--floppies and tiny hard
drives. FAT16 could be used only for drives/partitions up to 2GB
(which is why it has essentially been replaced by FAT32). FAT32 can
address much larger drives/partitions--up to 2TB.
Back in the days before FAT32, what we now call FAT16 (to distinguish
it from FAT32) was often simply called FAT, because except for FAT12,
which was primarily used only for floppies, there was no other kind.
Some people still use the term "FAT" to refer specifically to FAT16,
as opposed to FAT32, but in my view, that usage is now inappropriate
and confusing.