What is a constituional monarchy? How was this different from the monarchy of Spain, France, Russia

"A constitutional monarchy is a form of government in which a monarch acts as head of state within the parameters of a written (i. e., codified), unwritten (i. e., uncodified) or blended constitution."

"Spain: Declining absolute monarchy, Catholic. The throne lapsed into uncertain inheritance in the early 1700s (sparking the "War of Spanish Succession" in which Louis XIV installed a Bourbon claimant) and never wholly recovered its power. The Spanish monarchy resisted most reforms and innovations associated with the Enlightenment."

"France: Strong absolute monarchy, Catholic (Bourbon Dynasty). Louis XIV and Louis XV reigned during most of this period and built up centralized royal power, greatly diminishing the strength and independence of the nobility. Enlightenment culture and philosophy were celebrated and even supported in France, but there was no serious effort at instituting political reforms until the 1770s-80s under Louis XVI, under whom the French Revolution started (at least partly in reaction against the disruption caused by free-market "physiocratic" economic reforms) "

"Russia: Absolute monarchy, Orthodox (Romanov Dynasty). The Russian empire was vast and considered backwards by most of Enlightenment Europe. Tsar Peter the Great rigorously embraced Enlightenment culture and used his power to centralize the state, made the nobility subservient to the monarchy, and modernize (and Westernize) Russian citiies and their economy. Peter also greatly cracked down on the Russian church, though under his successors Orthodoxy became a powerful "pillar" of the regime. Most of the Russian tsars of the 1700s (including Peter and later Catherine the Great) were considered "enlightened despots" who very much wanted to be a part of European (particularly French) culture."