Demo is set up to mirror Live account. The only differece is emotions, because you are not trading real money, you tend to not take things seriously as there is nothing to lose. In real accout, depending on which broker type you are with, you might get requotes and slippage translating into losses.
Slippage is the difference between the price a trade is closed at and the price you placed the stop loss at. Slippage is a negative effect and on demo accounts all transactions are instantly executed as they are not actually being placed in real environment.
Also demo accounts do not take market time into consideration. If you place a trade on a demo account it will be opened instantly with no negative difference from the price you clicked on. However in live accounts, one can get requote. This is the difference between the price you want to open the trade at and the price that is now on offer to you.
It is always advisable to stay on a demo account until one understands what he/she is doing, and until they are making a constant profit, at least over the longer term time frame. To many people don't demo for long enough and then ask why there real account does not mirror the performance of their demo account.