The efoil and hydrofoil share the same root, so one can easily get confused when talking about these two devices. 

So what are the differences?

The hydrofoil has been around for quite a while now. It works on the same principle as airplanes and more specifically, the aerofoil system in aircraft. Like the aerofoil, the hydrofoil has wings, albeit underwater. Once the device gets moving, the stream of water passes through in such a way so as to generate a force that lifts the board (or airplane) upwards. 

The efoil, or electric hydrofoil, is based on the concept of the hydrofoil, the sole difference being the propulsion method. While the latter is driven by energy from wind or waves, the efoil has a battery and an electric motor. It is not very difficult to determine the differences with that knowledge.

Below is a short table that compares the characteristics of the two types of devices: 

In general, the idea behind the boards is the same, but there are slight differences in the construction. The efoil wings are larger compared to the normal wings, as they have to bear the heavier weight of the board and battery. The mast is a bit thicker, as it needs to encompass the cables. The volume of the board is bigger, as it needs to fit the battery compartment and the electronics box. But don’t be scared by the difference in the metrics. The efoil compensates with a powerful motor, which has the capability of supporting speeds of up to 45 km/h - just as much as the speed you would go with if you were kitesurfing with a hydrofoil board.

What's more, the battery lasts up to two hours and the effort is smaller, so you can enjoy this sport for quite some time. 

Safety is also a key feature when it comes to electric hydrofoils 

where the surfer controls the speed at every moment with the help of the remote controller that they hold in their hand. In normal foils, you are constantly dependent on natural factors, which means that you cannot really control the conditions and things often get out of hand, especially if you are a beginner.

If you are thinking about jumping into one sport or the other, you should definitely start with an efoil. They are much easier to learn, especially if you learn on boards focused on beginners and non-athletes like those developed by SiFly. Also, if you first learn how to balance on an electric hydrofoil, surfing on a foil will come much more naturally, you won’t have to think about your board and you will be able to focus on mastering the winds or waves.