The main difference between a futures contract and equity ownership is the fact that a futures contract has a limited window of availability by virtue of the expiration date.
There are many more differences between futures and equities, but one big thing to keep in mind is the leverage you can get with futures. The CL contract he's talking about is for physical delivery (or receipt) of 1000 barrels of WTI light sweet crude oil in Cushing, OK. The front month contract is currently trading around $97/barrel so the total value value of one contract is about $97,000. The CME will let you buy or sell a single contract with a little less than $4,000 worth of margin. That's like 20x or 25x leverage if you are trading close to the margin limits. I guess what I'm saying is that it's a pretty easy way to blow yourself up if you don't know what you're doing.