What is the difference between the thorax and the diaphragm?

Answer 1

thorax = the part of the human body between the neck and the diaphragm, partially encased by the ribs and containing the heart and lungs; the chest.

diaphragm = a body partition of muscle and connective tissue separating the chest and the abdominal cavities.

Answer 2

the lungs is where gas exchange take place,

the thorax is where the lungs are located