I'm new to futures. what is the difference between soybean (ZS) and soybean (S). i know ZS is traded on eCBOT and S is traded on CBOT. trading time is from 6:31 PM to 1:15 PM. and S is traded on CBOT and trading is from 9:30 AM to 1:15 PM. the trading hours are different. what else is different? what is similar or the same? if you trade, which one will you choose to trade? can anyone help me?