In terms of ranking among the peerage of Feudal society, the royal family was at the very apex of the hierarchical system. So you had a King, or Emperor, followed his vassals. These usually went from Duke, Count, Viscount, Marquis, Baron and Knight in descending order. The royal family, meaning the King, Queen, Prince and Princess were above the nobility, represented by the ranks I previously mentioned.Now here's where things get muddied... During the Renaissance, particularly in Machiavelli's Il Principe, the title of "Prince" is given to any high enough ranking noble who holds a position of command. For example, a Cardinal is considered a 'Prince of the Church', but so too can the ruler of a Principality, such as Monaco, be considered a Prince without being a member of any royal family. This was specific to certain areas of Europe, particularly in the boot of Italy where the word still carried something of the meaning it had during the Roman Empire of 'Princeps'.