Conquistador: a comparative example can be shown by examining George.
President George Washington, through voluntary action abdicated his position as leader of his newly formed country. King George III died at Windsor Castle after sixty years of rule. No one force Washington from his position at the top. Only death could coerce Frederick from his. Upon hearing of that once former rival would decide to retire by his own free will, the good king is quoted as saying, " If he does that, he will be the greatest man in the world."
A ruler owns his subjects. A leader represents his citizens. I was raised in a part of America that had a strong North American aboriginal influence as well as an international one...
Here, read the link below and reflect on your avatars namesake as well as your question:
http://firstpeoplesvoices.com/lives.htm
"A society can function without a ruler."
I would like to see an example of that. When you break it down, no society has ever done that by choice. If you think about it, since it derived from greek, you can imagine that rulers can be assasinated, die, or are indisposed for whatever reason. In this case, a regent takes over in place of that ruler.