Some people can become confused if there is any difference between ability and skill mainly because the differences are not that obvious. When you say ability, this may be something that you already have from the very beginning.
This means that you have something that is innate and you may want to just enhance it. It will be easier for you to enhance something that is already there. When you say skill, this may be something that you will acquire when you try to learn new things.
For example, you may have the natural ability to cook but you would need to have the right skills in order to work better. The skills can be learned when you check out various reviews or when you try to teach yourself.