Government

Descriptions of government on the BIRTHRIGHT wiki follow a pattern that describes who governs as an adjective, and how many govern as a noun. Further, the adjective which describes who governs should take "...cratic" form, using terms based on the Greek word kratia meaning "rule". The noun should use the form "...archy" based on the Greek verb stem "arch-", meaning "to rule". This is not a firm rule, but its use will make understanding the distinction between who governs and how many govern more clear.
So an Aristocratic Monarchy is a government where one person rules (monarchy), and that person both comes from the class of and draws on the service of a landed nobility (aristocratic).

Governments may be the rule of one person (Monarchy) or small group (Oligarchy). Rule by the many is generally not likely since the power of a blooded scion to collect regency makes government by one or several blooded individuals much easier to sustain.
Governments nearly always have a single regent as their head. However, some domains require by law or tradition that the regent consult a council of some sort (Oligarchy). Sometimes a regent is able to act more or less unfettered by formal institutions (Monarchy). On rare occasions, political institutions have collapsed entirely and there is no government (Anarchy).
Republican forms of government, in which a council of leaders is so strong that they no need for a single regent, even as a figurehead, are an extreme form of Oligarchy.
Before Deismaar, when it was still possible to form small, tribal governments, it was possible to have a government by the many. Such polities had to be small, since gathering many, limits the total size of the polity. Many of these governments were a form of meritocratic government where one was selected for office by the esteem of the community (Timocracy). In a few, selection of officials was done by fortune, such as in the form of a lottery (Democracy).

Governments may draw power from a group of landed nobles (Aristocratic), temple priests (Theocratic), magical sources (Magocratic), or based purely on wealth (Plutocratic). Some governments do not draw support or rely principally on any one group, but rely only on the regent himself (Autocratic). This form of government often describes a tyrant or dictator. A mostly theoretical source of power is talent (Meritocratic) but these generally only describe new states, because they quickly become Aristocratic. A government's power may also depend on a pyramid of subordinates (Feudal) each owing loyalty and aid to their superior, ultimately culminating in the regent. Some governments are little more than parasites on their people (Kleptocratic), existing only to extract as much as possible from the people.
Generally, but not exclusively, Temple domains are Theocratic, and Guild domains are Plutocratic.