"What's the difference?" In your examples, they are interchangeable. However, that does not mean they are always the same: "Certain" also has a meaning of something determined, while "sure" has a sense of safety and security. For example, you can say "I know a certain person" (a particular person), but "a sure person" gives a very different meaning (ie. a confident person). Conversely, "He operated the controls with a sure hand" means his control was confident and steady. Change "sure" for "certain" and you get a different meaning, ie. he specifically chose to use either his left or his right to operate it. Maybe the other hand was busy.

In terms of practical use, the words are basically the same.

Particular thanks for (to?) correcting me :)

And the question would be What is the difference?

Haha thanks. But it is still confusing some. Why there are needed so similar words.