I have one question, please, could you explain to me the difference between

he folded his arms
he crossed his arms

No difference. He would look the same with arms crossed or folded, just a different way of expressing it Emotion: wink

They are different but could be the same. Folded arms implies that they are lying across the abdomen, chest, or lap (if sitting). Crossed arms could be the same as folded but not if they are held up and crossed or behind the back or any position where they are crossed but not laying flat across the chest. Also, folded usually means interlocked while crossed arms don't require they be interlocked. Think of an Egyptian mummy which holds an instrument in each hand. The arms are cross and laying flat against the chest but are not interlocked so they are not folded.