Hmm, in fact, CHEST voice is called chest voice because the size of our vocal ZIP (air tract) is bigger than usual, more air gushes out from within, thus producing a THICKER sound.

As for HEAD voice, the vocal ZIP (throat hole), is narrower, producing a THINNER sound, when you hit some very high notes within your range, you will feel your rear skull vibrating.

As for DIAPHRAGM SINGING (singing from your stomach lol) that many people say, its just matter of CONTROL of your AIR FLOW from below your chest till out of your mouth. There must be a good flow of air movemet when you sing, try feeling it NOW.

If you CANT feel any air flow or air flow is being cut from below when singing, try INTENTIONALLY opening your VOCAL TRACT (lubang kerongkong), by lowering your LOWER JAW, it opens up naturally when you do so.

(This explains why BEST singers open up theyre mouth real wide when singing, to produce the best RESONANCE/ sound)