Different futures varieties have different meanings and represent the main contracts. For example, copper 5 tons, strong wheat 10 tons, and fuel oil 50 tons. The difference between futures and stocks lies in its margin trading. Take copper for example. The deposit for primary copper is-70,000/ton *5 tons * 15% = ...

Moreover, futures can be traded at T+0 and can be bought and sold on the same day. I hope these are helpful to you.