Legends are defined by a story in which involves people from a historical background (Robin Hood) and their actions. The story is more or less based on people who have existed in the past that have completed tasks or certain deeds that no other man or woman could achieve. Some stories may have been exaggerated over the years to make the story more exciting and interesting.
Myths are somewhat similar to Legends as the story mainly focuses on an individual. The difference here is that they are more than enough fictional stories to try and explain why the world works in the way it does. As mentioned in another post, these stories are usually based around a Gods, either it be Greek, Egyptian or Nordic. For example, Zeus is a Greek God of thunder. If a thunderstorm were to appear out of nowhere, people would believe that Zeus is angry and showing his wrath.
Lastly we have Fables, although many people don't understand the meaning of the word and mistreat the story as either a Legend or Myth as it often refers to a fictional or fantasy story. The real definition of a Fable story refers to a fictional story to which animals, creatures, and objects that have been anthropomorphized, meaning they have humanistic behaviors.
References -
1) Robin hood Statues in Nottingham - http://gallery.nen.gov.uk/assets/0611/0000/0061/p1000052_mid.jpg
2) Picture of Zeus - http://static.comicvine.com/uploads/original/5/58339/1163902-zeus.jpg
3) Fable book cover - http://www.takdangaralin.com/wp-content/uploads/2009/09/fable1.jpg
1) Robin hood Statues in Nottingham - http://gallery.nen.gov.uk/assets/0611/0000/0061/p1000052_mid.jpg
2) Picture of Zeus - http://static.comicvine.com/uploads/original/5/58339/1163902-zeus.jpg
3) Fable book cover - http://www.takdangaralin.com/wp-content/uploads/2009/09/fable1.jpg