The key to understanding the difference, if you are so inclined, is to google “djia futures fair value” and poke around a little. The price of the futures contract, which is what you are seeing now, can vary from “fair value” in either direction. That price takes into account not just the prices of the stocks, but dividends and how much time remains in the contract.
I don’t think the average investor really needs to care about the difference (I don’t) — it’s for the big money guys who run the computer buy and sell programs.
Better make that two terms to google for: “djia futures” “fair value” instead of all in one phrase.