let's just put it in real life context..
let's say, the countries of Fire, Earth, Wind, Lightning and Water are the 5 most powerful kingdoms in our reality, (Spain, France, Great Britain, the Holy Roman Empire and the Papal States).. the Fire Daimyo is equal to that of the King of Spain.. he governs the land and its laws, its economy and its people.. basicaly, he's king.. now, the Hokage is equal to the Prime Minister or Minister of Defense which holds and governs the country's military strength.. now, the position of daimyo may be hereditary or something, but the position of kage is appointed.. now, the daimyo may appoint or nominate someone he likes to be hokage, but it is still the choice of the Jonin Council whether that position would be official..
in context, they are equal, but in reality, the Hokage was more power.. the Fire Daimyo may be the one who pays and finance the Hidden Village, but the entire system and politics of the Hidden Village is under the Hokage's control.. in short, the Fire Daimyo rules the Land of Fire, but the Hokage rules Konoha, and Konoha is the military strength of the Fire Country.. it would be relatively easy for the Hokage to use the military power she controls to take control of the entire Fire Country and let the Fire daimyo rule akin to a puppet ruler.. He/She who controls the country's military force wields the greatest power.. remember what happened to Russia? it was easy for Vladimir Lenin to overthrow Czar Nicholas II..