How do you tell whether a filename is FAT32 or NTFS?

How do you tell whether a filename is FAT32 or NTFS?

My harddisks are all NTFS.

What happened was I was transferring files when suddenly the filenames of some of the files changed from their original long filenames into short filenames that looks like some kind of FAT32 filename.

I read somewhere that FAT32 filenames are short and I suspected that the filenames were somehow converted from NTFS to FAT32...

FAT32 supported long file names as well.

The file system itself is either FAT32 or NTFS. The files themselves aren't inherently one or the other. For example, you could put the file onto a USB drive and copy to a MAC or to Linux or to Windows and the file will remain the same...even though the underlying file system on all 3 systems are different.

Regarding the "short filenames" I mentioned, I was thinking along the lines of this:
8.3 filename - Wikipedia, the free encyclopedia

Now I'm confused.