Click on the links and listen to the different sounds.
Notice that in /ʃ/, there is no voice from the throat. Instead, you can feel the air coming out from your mouth. This is known as a voiceless sound (there is no vibration in the vocal chords). It sounds like as if you were asking for silence.
When pronouncing /dʒ/ there is voice from the throat. This is known as a voiced sound (the vocal chords vibrate). The /dʒ/ sound begins with a complete stoppage of airflow. Practice by pronouncing the /ʒ/ sound for an extended period of time while stopping and releasing airflow.
Below, some examples for both sounds:
As you can see, the /ʃ/ sound can be written with sh, s, c, ch, ss. The suffix -tion is also pronounced with this sound.
However, the /dʒ/ sound can be spelled with j or dg(e), g(e) depending on the position of the sound in the word. Notice that the final -e is not pronounced.