This isn't anywhere near as true as it used to be, but I consider one difference between x86 platforms and ARM platforms to be whether or not booting involves the use of a mask ROM at reset to initialize the system. If we ignore the developments of Intel's ME and AMD's PSP, x86 processors start executing from EEPROM. The code that is stored there can be in whatever format because the processor just executes it, no questions asked. At reset on an ARM chip, things are more complicated. The CPU begins executing code stored in an on-die mask ROM and this code may or may not pass off execution to code stored in a mutable medium depending on the chip's design. The code that it'll jump may need to have a header, even if it is stored in a memory that is XIP-capable.
There are a few instances of ARM-based processors that will start executing code that is stored in EEPROM. The STM32 line of microcontrollers fits this design. However, there will still be some kind of read-only code on the chip that can be booted from if the pin configuration is right. On the STM32 chips there is an "embedded" bootloader on the chip that is used for programming the internal flash.
My question is this: do there exists ARM chips that lack any sort of boot ROM and will behave at reset in the same way older x86 processors used to operate? What situations would they be used in?