What were the key political and religious differences between France, Russia, Prussia, and England during the period 1450–1750?

Given that this question is very broad as stated, it might be best if we approached it in an inverted form by first focusing on what the similarities were among these states during the period referred to. We can then extrapolate the primary or central differences as negatives and perhaps can grasp them better in that way and arrive at a concise solution to the question at hand.
France, England, and Russia all, during that 300-year span, emerged from periods of internal and external strife to become unified, powerful nation-states. France expelled the English in the Hundred Years' War, then settled its internal religious conflicts in the aftermath of the Protestant Reformation and became a unified Roman Catholic kingdom under an absolute monarchy. The Russians, after expelling the Tatar overlords who had controlled the country for 200 years and then going through a period of internal disorder known as the Time of Troubles, emerged as an absolute monarchy under the Romanovs and secured its position as a European power under Peter the Great.
England, during the same overall period, 1), emerged as a stable state under the Tudors after the conclusion of the Wars of the Roses, 2) seceded, under Henry VIII, from the Roman Catholic church, 3), became a world power with the defeat of the Spanish Armada by Elizabeth I, 4) went through the period of the Civil War, the Commonwealth, the Restoration of the monarchy and the Glorious Revolution to emerge as the beginnings of a constitutional democracy, and 5) through the Union Act in 1707 merged with Scotland to become a united kingdom encompassing the British Isles—a single state containing four countries: England, Wales, Scotland, and Ireland.
Prussia did not emerge as a major power until the end of the period under discussion here, and was not a nation-state in the same sense as the others because 1) it was only a part of the German lands (the Holy Roman Empire at that time) as a whole, and 2) it held territory to the east, outside the boundary of the Empire, where non-German-speaking peoples lived.
In each case the similarity is that these four states gained and consolidated power during the centuries in question, settling internal disorders and conflicts with outside powers, and became stronger, essentially creating the model of the modern state as we know it. Yet in every other respect, there were crucial differences among them. In religion, France was Roman Catholic, England had its own independent church that was separate from the Protestant churches on the Continent, Prussia was mostly Protestant, and Russia was Eastern Orthodox. Politically, England was an incipient democracy under a Constitutional monarchy.
France and Prussia were absolutist monarchies but with the vestiges of feudalism supplying a counterweight to the monarch in the form of the nobility and the local regional control it exercised. Russia's monarchical system was more absolute than that of the others because the feudal system, with its de facto division of power between the nobles and the monarch, had not existed to the same degree in Russia as in the West. The Czar's power was thus more total than that of the monarchs of France, Prussia, and especially England, where, as stated, the beginnings of democracy were already in existence.

The complexity of this question allows only a limited response in this venue, however, in general, the key religious differences between the populations of France, Russia, Prussia, and England can be itemized as follows:
The people of England, for the bulk of this time period, were primarily adherents of the Church of England, established in 1535 as the kingdom's official church following a schism with the Roman Catholic Church. During this nascent period in the development of Anglicanism, the practical theological differences between it and its parent church were limited.
The people of Russia, and the Russian royal court, during this time period were adherents of Orthodoxy, one of the two great, pre-Protestant strains of Christianity.
Prussia was the first European state to adopt Protestantism, becoming an official Lutheran nation in 1525.
France was, and continues to be, a majority Roman Catholic country.
In terms of political life, England, Russia, Prussia, and France were all monarchies, however, several unique aspects in their political structures can be identified:
The power of the English kings was limited by parliament; specifically, the Crown was unable to levy taxes without consent of the legislative body. In addition, English jurisprudence was based on common law.
The power of the royal court was less restrained in France. The Estates-General, a legislative-like body, existed off-and-on during the time period 1450-1750, though was a far weaker institution than its counterpart in England and usually filled a role that was more consultative rather than legislative. French jurisprudence was based on civil law.
In Prussia and Russia royal power was almost absolute.

What were the key political and religious differences between France, Russia, Prussia, and England during the period 1450-1750?
This question is of enormous scope and is, therefore, difficult to answer concisely. One could write a multi-volume work on the topic. One might approach the topic by identifying major religious and political developments in each country. You can then identify the major differences.
Overall, the period in question was one of political consolidation and centralization with a heavy element of religious conflict and violence. In general, royal power achieved greater control over religious institutions as time progressed, which led to greater religious uniformity.
The Protestant Reformation gave birth to French Calvinism, which gave rise to political conflict and religious wars between the Huguenots and Catholics in the late 1500s and into the 1600s. The Catholics were ultimately victorious and, while religious toleration was granted in the short-term with the Edict of Nantes (1598), it was revoked in 1685 by King Louis XIV "the Sun King," who took leadership of French Catholicism. Louis also developed the French bureaucracy and centralized the French monarchy to previously unseen levels.
While Russia did not have a Reformation as such, western influence following the integration of the Ukrainian lands led to a cultural shift that precipitated the Old Believer Schism in opposition to the reforms of Patriarch of Moscow Nikon. The Old Believers, who opposed a revision of church ritual, were suppressed by Tsar Alexis. Alexis then consolidated power and asserted authority over the Russian Orthodox Church by defrocking Nikon. This state dominance was formally instituted under Alexis' son, Peter the Great, who made himself the administrative head of the Church in 1720.
Prussia started out as a duchy of the Kingdom of Poland. Frederick William of the Hohenzollerns wrested Prussia from Polish control, creating the small state of Brandenburg-Prussia by 1657. Prussia became a separate kingdom only in 1701, with Frederick III as the king. His son, Frederick William, established Prussia as a major military power in the mid-1700s and administrative apparatus fit for the absolutism of the age. Prussian rulers were Calvinists, but the population was a mix of Lutheran, Calvinist, and Catholic. The kings perhaps had a relatively hands-off approach toward religion, but Protestantism was clearly favored, with Catholics barred from high government positions.
In England, Henry VIII's Act of Supremacy (1534) established the Church of England as an entity independent from the papacy; it also established the king of England as the head of the Church of England. Following Henry's death, Protestantizing reforms under Edward VI gave way to Catholicism under Queen Mary (with the persecution of Protestants), and then to a new Act of Supremacy (1559) under Elizabeth (with the persecution of Catholics). In the end, the Anglicanism and the Church of England became entrenched. English absolutism peaked with Charles I but the so-called Glorious Revolution of 1688 granted more authority to the Parliament, while also ensuring that all subsequent kings of England would be Anglican.