What is the difference between the methods for writing .ISO to USB via UltraISO and via dd?

Question

Command line

When writing a Windows image to a USB flash drive via dd (/dev/disk2), the installation does not start from it. If you boot in UEFI mode, then starting is possible, but older laptops do not support this mode. When recording via UltraISO, there are no such problems, everything loads normally. There are suspicions that UltraISO uses some other recording method and writes not only files to the USB flash drive, but also some additional boot blocks to it.

Answer 1

UltraISO is adding its bootloader, you can see (I don't remember exactly where) in one of the menu items there is a "Bootable CD / DVD" item and you can create an empty bootable disk there.
DD writes "as is".