You may have wondered what's the difference between the Canon 580EX II speedlight and the YN 568EX II speedlight by Yongnuo. The short answer is not as much [difference] as you might think. The Canon speedlight include a few options that truly makes it more versatile for remote locations, like the ability to add an external battery pack.
Conversely, the YN 568EX II speedlight offers sound, which isn't found on the 580EX II. In terms of function - the ability to consistently light your subject - I could find no noticeable difference.