AFAIK on all the thumb drives I have (about 5 to 6) they are all the same. Under 2Gb thumb drives are prepackaged with fat16 filing system which can only address up to 2Gb. Larger thumber drives than 2Gb always formatted in fat32. There is nothing to stop a user to re-format it with other filing system but the journalling system with frequent read/write is known to kill the drive prematurely.

An USB device is bootable if a a boot loader can see it. For that the "USB legacy support" has to be enabled in the Bios because boot loaders cannot installed a driver, like a kernel can, to help it to detect a USB device. Whenever a mobo refuses to boot a USB drive I would check its Bios, enable the USB legacy support and the device will start to boot.

The OP problem is the iso file he/she booted was supposed to be burn into a CD. It may contain instructions to copy files from various CD disk directories. Thus the booting process hangs when the necessary files are not available. There is no communication with the CD. He/she does not have a problem if a copy of the iso has been burn and inserted in the CDrom because the required files become available.