Board Thread:Naruto Discussions/@comment-24898250-20140730025315/@comment-24531362-20140803063407

The point about stamina is that stamina is a real-world term, used to explain (in real-world terms) the base amount of energy a person has. If you run a mile and are really tired afterwards, you are out of stamina. Chakra, as I understand it, can be used to increase stamina artificially, allowing one to run faster and farther without feeling drained. Hence, though the two are different, they are related in the context of Naruto.