Breath of things and voice of all things are two different concepts
Breath of things is a swordsman technique that allows the user to focus and listen to the inner workings of things allowing Zoro to cut steel
Voice of all things is a special technique even rarer than conquerors that only like 5 people have been shown to have
Roger
Oden
Momo
Luffy
Joyboy
This technique allows them to talk and communicate with everything its how momo is able to command Zunesha, how Luffy was able to hear the sea kings, etc etc