The main difference is that you trade using real funds when trading on the live account, while demo accounts use virtual money with no real value to trade.
Despite this, the market conditions for demo accounts are exactly the same as they are for real accounts, making them ideal for practicing your strategies.
While all the features and functions of the real account are also available for a demo account, you should keep in mind that simulation cannot replicate real trading market conditions. The speed of execution is the same for real trading accounts as for the demo accounts.