NASM - Why do I get different byte codes for one asm file (compilations to elf and binary output to a file)?

Question

assembler

Hello!
There is a simple asm code (only for an example - for point ... although it was possible to consider "Hello world" as well).
xor eax, eax
I do the following:
1. I compile to elf and look at the code section (opcodes are the same as x32):

nasm -f elf64 xor.s -o xor_x64
objdump -d xor_x64

2. Simple output of this "file to file" (default format is binary):

nasm -o bin_xor xor.s
hexdump bin_xor

I get this output:

Why did the byte 0x66 appear? Should the bytes in this section match what I got in the binary output? If not, why not?