A Masters by research course at York involves a focused research project that is normally assessed by an extended written piece of work known as a thesis and often an oral examination.
You'll have more independence than on a taught Masters course and can choose your own research topic. You won't be working in isolation though. A supervisor will advise you on your project, and additional support will be available from your department and York Graduate Research School.
Most Masters-level programmes are taught courses. But a Masters by research offers an alternative route to getting a Masters degree and gives you a taste of what studying a research degree is like without having to commit to a doctorate. There are several other differences too; from how to apply to what it will cost. Once you understand all the differences you can decide which is the best for you.