Too many people use ranking questions and rating questions as if they are one and the same thing. This is quite a serious error, since they are very different. Understanding the difference will also allow you to better grasp when to use each type of question.
With rating survey questions, a person is asked to compare two separate parts. Usually, they have to do this on a scale of one to 10, although others prefer one to five or actual terms (very important, important, somewhat important, neutral, somewhat not important, not important, completely not important). Different things can be measured with these questions, such as how happy people are with a service, value for money, staff presentation and so on.
Ranking questions are very different. Here, they are provided with a list of objects and they have to place these in the right order. For instance, with a rating question in a restaurant, people will be asked to rate the food, the service, the value for money and the ambiance. With ranking questions, they are provided with four items (food, service, value, ambiance) and list these in order of how much they enjoyed them. As such, ranking questions are often more limiting than their rating counterparts, because you can score everything equally when rating them, whereas elements have to take precedence when ranked.
Although complex to understand, you must take some time to get to grips with the difference between ranking and rating, not in the least because the data they provide you with can affect the results of your questions greatly. For instance, with the restaurant example, when someone ranks the food as the lowest, this does not necessarily mean that people did not enjoy the food. This is why answers and piping are also very important, so you can ask further questions in your online survey.