What's more powerful a warlord or a lord? And Also What's more powerful a King or An Emperor?

A lord -- meaning a peer such as a duke, earl, etc. -- could BE a warlord. Or, a warlord could simply be someone who has taken military and civil control of a given area without actually having a title to which he was born. So, everything depends on the identity of the warlord. If he's a non-titled person who has seized power somewhere, real lords in other areas may not be able to do anything about it, even though, technically, they possess higher status and greater power than he does. "Lord" is also something of a generic term that is used in many different ways in the UK. A duke's younger son is called "Lord Firstname Lastname," but peers of various ranks may be addressed or referred to as "Lord Titlename". For example, the Marquess of Canfield would be addressed as "Lord Canfield" in a letter or to his face. Now, Kings reign over kingdoms, but strictly speaking, emperors have traditionally reigned over entire empires, which may include kingdoms, duchies, principalities, etc. This was the case with the Holy Roman Empire, for example. (There were also, of course, kings who were NOT subordinate to an emperor, whose kingdoms were entirely independent of an empire.) All in all, however, given that emperors commanded much more extensive territories and resources, they were once more powerful than kings, even kings who were not subordinate to them, whose kingdoms were not part of their empires or any other emperor's. But today, the emperor of Japan doesn't actually reign over an entire empire of the type I described, he is not more powerful than kings (in fact, in many ways, he is LESS powerful than some western monarchs), and the monarchs of other constitutional monarchies do not consider him to be superior to them in rank.

Normally a Empire is bigger than a kingdom . Dukes are high ranking Lords are "ten a penny ".

neither is more powerful as such, a lord could actually be a warlord. Emperor Duke

A warlord would be more powerful than a common lord, but less powerful than some lords, and, as mentioned, might very well be the same person. An Emperor is usually more powerful than a king, but, you know...Hailie Selassie called himself an "Emperor", but he was less than Queen Elizabeth. So there are exceptions. In many cases, the Emperor ruled over several kings, but that depends on the size of the Empire, and the power of it. Some kingdoms are larger, richer, and more powerful than some Empires...

Warlord vs. Lord - It depends. A lord has control over a warlord, but since a warlord controls the lord's army, they can overthrow the lord. King vs. Emperor - They are the same thing ultimately, just called different names in different countries. Duke vs. Lord - A lord is more powerful.

To simplify as much as possible: A King and an Emperor are the same. You can't compare Lords and warlords- lord means born to that title, warlords gain that power through military strength. A country can have one, both, or none. There is no standard for their power, so it can't be ranked. A Duke is a type of Lord.