Why does objdump behave differently on macOS and Linux?

[Peng Yu]

$ /usr/local/opt/binutils/bin/objdump -v
GNU objdump (GNU Binutils) 2.36.1
Copyright (C) 2021 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) any later version.
This program has absolutely no warranty.
$ objdump -v
GNU objdump (GNU Binutils for Debian) 2.35.2
Copyright (C) 2020 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) any later version.
This program has absolutely no warranty.

I have the installation of objdump on macOS and Linux. But the results
are not the same. On macOS, the result shows "ret". But on Linux, the
result shows "retq". Why is it so? Thanks.

$ echo ret > 1.asm
$ nasm -felf64 1.asm
$ /usr/local/opt/binutils/bin/objdump -w -d 1.o
   0:	c3                   	ret

$ echo ret > 1.asm
$ nasm -felf64 1.asm
$ objdump -w -d 1.o
   0:	c3                   	retq

-- 
Regards,
Peng