Would you please include your categories? THis would make the question much easier to answer. However, Robin Hood could be categorized as an adventure, as a moral story, as a legend, and possibly even a folk tale.
I would categorize Robin Hood as a Legend as told by Howard Pyle. We know the stories were around long before Pyle but he collected them into a novel, much like the Grimm Brothers did for Fairytales.
That could fall into the category of an adventure story.
The Merry Adventures of Robin Hood could be classified as a folk tale, seeing as how he is portrayed as the hero of the people. However, a condition for a true folk tale is that the original author is unknown, meaning one of the people, which makes the story a people's property.