The Protestant Reformation was the 16th-century schism within Western Christianity initiated by Martin Luther, John Calvin and other early Protestants. It was sparked by the 1517 posting of Luther's Ninety-Five Theses. The efforts of the self-described "reformers", who objected to ("protested") the doctrines, rituals, and ecclesiastical structure of the Roman Catholic Church, led to the creation of new national Protestant churches. The Reformation was precipitated by earlier events within Europe, such as the Black Death and the Western Schism, which eroded people's faith in the Catholic Church and the Papacy that governed it. This, as well as many other factors, such as the mid 15th-century invention of the printing press, and the fall of the Eastern Roman Empire, contributed to the creation of Protestantism. Today, protestantism has dialog with the Catholic Church in many ways, and some branches are considering reunification.The Roman Catholic Church responded with a Counter-Reformation initiated by the Council of Trent, the most important ecumenical council since Nicaea II 800 years earlier. At the time, there had not been an ecumenical council since Lateran IV over 300 years earlier, a length only to be matched by the interval between Trent and Vatican I, and spearheaded by the Society of Jesus. In general, Northern Europe, with the exception of Ireland and pockets of Britain and the Netherlands, turned Protestant. Southern Europe remained Roman Catholic, while fierce battles which turned into warfare took place in central Europe. Modern Catholicism and Protestantism are quite similar, differing mostly on the reverence for Mary, purgatory, and the place of works and the leadership of the Pope. There are minor differences besides these which serve as barriers to full unification, but on the major doctrines of the faith, there is essential unity. Notwithstanding, there are both Catholics and Protestants who continue to battle over these differences, as if it pleases God in some fashion to have brethren so arguing and divided. Such division is emblematic of the growth of the church; it is easy to be unified with a small faith, but one that is as large as Christianity has centrifugal forces that overcome the centripetal ones. From the wiki- reformation
There aren't too many similarities, given that the reformation that the Catholics did, was to clarify issues, and deal with some corrupt bishops who had been commiting the sin of simony by selling spiritual things such as indulgences, unfortunatly so many people now believe that the Catholic church as a whole did this, when in reality, it was simply a few corrupt employees. Whereas Martin Luther, the so called reformer, openly admits in his writings, that his only purpose, was essentially, to start a war, and make himself the authority by taking power, not to reform or fix any problems.
The difference between the catholic reformation and protestant reformation was their reasons for reformation. The Catholic reformation was as a response to the protestant reformation as the Protestants had accused them of indulgences. On the other hand, the similarity was that they both aimed at purifying the church through the reformation.