In Naruto, Yamato called Kakashi as Kakashi-sama, whereas Naruto as Naruto-kun.
Previously, I thought that sama was for equal or higher rank shinobis while kun was for junior rank shinobis. But I noticed that I might be wrong as Hinata too called Naruto as Naruto-kun.
I found some general answers on Yahoo! Answers, but is there a specific reason why they did that in Naruto? What's the actual meaning of sama and kun?