What is the difference between burning in ISO image mode and DD image mode in rufus (and not only)?

Question

ISO

Today, under Windows 10, it was necessary to create a bootable USB flash drive with Ubuntu 21.10. I did it as usual in Rufus and by clicking on the "Start" button I saw this notification:



Tell me, what is the difference between these recording modes?

PS
I read that "dd" copies information bit by bit, but when writing in ISO mode, what happens? Everything is the same as in "DD", only rufus adds some kind of bootloader?

Answer 1

dd copies the entire "disk"\partition and it doesn't care if there are files there or there is no
entry in the ISO - only real data

Answer 2

ISO mode is essentially an image burning mode, with the ability to replace files, check bootloader versions, detect errors, and the like.
DD mode is a direct bit-by-bit copy of information that will copy even existing errors in the image (or anywhere else).