The lights themselves are not more efficient. In fact a smart light will consume slightly more power than it non-smart identical equivalent, because it needs to feed its WiFi sensor as well.

That said, however, they are more efficient overall because they be controlled (in a smart way 😀 ) to turn on and off without having to remember. For example, you can make set the smart light to automatically turn off in the day.

If you are comparing smart lights (which are all LED) to non-LED lights, then they are definitely more efficient.

Smart lighting enables you to set them to turn off when nobody is home, so that is much more efficient.

Also, smart lights are dimmable and this also reduces the electricity use, which increases their efficiency. 

One way they are more efficient is that they can be turned on and off remotely, when you are away from home. So if you forgot to turn them off, you can look in your iphone and check, and if they are on then you can turn them off.