Русско-англо-русский юридический словарь

A personal union is the combination of two or more states that have the same monarch while their boundaries, laws, and interests remain distinct. (Wikipedia)

Real union is a union of two or more states, which share some state institutions as in contrast to personal unions; however they are not as unified as states in a political union. It is a development from personal union and was usually limited to monarchies. (Wikipedia)

A monarchy is a form of government in which a person, the monarch, is head of state for life or until abdication. The political legitimacy and authority of the monarch may vary from purely symbolic (crowned republic), to restricted (constitutional monarchy), to fully autocratic (absolute monarchy), and can expand across the domains of the executive, legislative and judicial. A monarchy can be a polity through unity, personal union, vassalage or federation, and monarchs can carry various titles such as king, queen, emperor, Raja, khan, caliph, tsar, sultan, or shah. (Wikipedia)