Is there any difference in meaning between these two sentences?:
1. They couldn’t understand him.
2. He couldn’t make himself understood.
In an exercise, I had the uderlined sentence given and I had to finish another beginning with “He couldn’t …” without changing the meaning.
My anwser was: “He couldn’t be understood”. I don’t know if my answer is correct or not because  was given as an only possible option. In my opinion  doesn’t mean exactly the same as . I feel confused.
Could anyone help me? Thanks a lot.