Knowledge of knowledge is what we mean in the traditional language. For example, gourd is a vegetable which is taste bitter, green in color These are information. But the name of the idea that I will use the information is knowledge. For example, a car color is black. This is an information.
But I will not do good to the car, how to drive it, that is the name of being aware of the beneficial or inefficient aspects of using information.
A more simple definition of knowledge is the awareness of the positive aspects of the information.
And, efficiency is the ability to do a job perfectly. You can do as much of a job as you can, as efficient as that.
But your question seems unclear to me. Knowledge and skill are two different things. There are many differences between these two topics. I gave the definition of two wins. Let's understand the difference.