carbon or aluminum

[tnctcb]

i bought a pse nova and the guy who sold it to me recommended carbon arrows.this bow has a 70# draw weight. my son wanted to shoot a bow so we went looking for something that had a light enough weight for him to pull now but could adjust to legal hunting weights later which is 35# in florida. the ultimate seemed to be a browning micro midas 3 but its only available in 20-30 or 30-40. he can only pull 20 pounds and since he couldnt hunt with 30 i wouldnt spend that much money. after looking at every bow they had the guy went to his catolog and found out that a pse spyder adjusts from 22 to 40 and he had 2 in the back he didnt know about. thats the bow he ended up with and the guy recommended aluminum with that bow. he said that aluminum hits harder but carbon is faster.is that true and what is the difference. what do you prefer.