Voice box and Vocal organ

Voice box noun - A cartilaginous structure at the top of the trachea; contains elastic vocal cords that are the source of the vocal tone in speech.

Vocal organ and voice box are semantically related. In some cases you can use "Vocal organ" instead a noun phrase "Voice box".

Vocal organ noun - Any of the organs involved in speech production.

Voice box and vocal organ are semantically related. Sometimes you can replace phrase "Voice box" with "Vocal organ", this phrases are similar.