A king rules his own nation ,

so focus in his own nation.

Counter his nation's enemy,

fight back to win his safety and security for his people and the nation.

He take the pride of his courageous behaviour and some time becomes hero in the view of the peoples.

But a real hero never sees any boundaries or border he is beyond of it.

He fights for justice, principles,truth and truth.

Real heroes never expect any appreciation or rewards.

Without any self lust,he always thinks for others.

Sometime they sacrifice their life for the truth and principles.

So both had their duties to fight

But one fights for their own inherent empire on the other hand areal hero fights for everyone .