Myths hold the beliefs of a culture within the safe confines of a story. Folktales are just as they sound: tales of the folks; the common people. Fairy tales are similar in theme but tend to either be grander hero journeys (think princesses and kings) or have some magical element.
Fairy tales generally have some sort of fantastic element, and might feature magic, imaginary creatures, and often a conflict between sides that are clearly good and evil. A myth has its basis in religion, often telling stories of supernatural beings or creators, and usually explaining some sort of natural phenomenon.
A myth is a traditional story explaining a historical or a religious phenomenon to the audience while folktale is a fictional story usually to entertain the audience, and sometimes even to teach them a life lesson.
A folktale (or folk tale) is a secular, fictional story that is passed down among common people and is often rooted in a superstitious belief. Unlike myths and legends, folktales are not considered sacred or truthful by storytellers (or story-listeners), and are usually told solely for entertainment's sake.
Fairy tales and Folktales are similar to myths because they are both stories that contain magic and have been passed down for a very long time. Myths contain stories of people with powers and magic that could not have actually been real.
Examples are fables, fairy tales, folktales, sagas, epics, legends, and etiologic tales (which refer to causes or explain why a thing is the way it is).
Greek Mythology's most famous tales
Mythology more famous tales
Myths are stories that are based on tradition. Some may have factual origins, while others are completely fictional. But myths are more than mere stories and they serve a more profound purpose in ancient and modern cultures. Myths are sacred tales that explain the world and man's experience.