difference between youth and adult helmet

Is there a difference besides size on adult and youth helmets?

I know to look for SNELL and ECE certified but other than that I have no clue.
 
I liked the one about the difference between having an emt pronounce a "victim" dead at the scene or waiting until they have them at the hospital in the ER to do it. Seems like the answer to that was about 13,000 dollars.
 
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