The Difference Between Stairs and Steps

People can just get a New Zealand driver's license straight away. If you're coming over from another country and you need to have a license in New Zealand, if you're here for holiday, you will have a period of time that you can get a special license. We thought we'd end today with some explanations between words that seem similar or that people often mistake. So what's the difference between a step and stairs? And there's another one you had too, right? Ceiling in roof.