When it comes to the electricity itself, there is no difference at all. A cheap electric supply is the same electricity, it's simply provided by a new supplier (unless you opt for green energy - more on that here). As suppliers buy and generate different sets of energy they also have different prices. What's more, you might be on a tariff that is simply more expensive, such as a standard tariff. If you decide to switch electricity don't equate a lower price with worse service.
Switching electricity supplier could shave pounds off your bills. But it’s not always about how much hard cash you could save. You might be fed up with poor customer service, you might want greater visibility of your usage through an app or you might want to choose your supplier based on their green credentials, or whether they supply a smart meter.