What are two differences Martin Luther and the Catholic Church had?

The differences that developed between Martin Luther and the Roman Catholic Church can be traced to several sources that were not necessarily related. On a theological level, one of the principle differences between them was Luther’s conviction that salvation for humanity could come through faith alone, and that no amount of good works could contribute to salvation. He therefore opposed the Catholic emphasis on works as an avenue to salvation, most famously the buying of indulgences as a way to atone for sins. Along with indulgences, however, Luther also condemned other similar practices (e.g. penance) as being unnecessary and theologically misleading.
Another major difference between Luther and the Catholic Church related to language. Since its establishment as the state religion of the Roman Empire, Western Christianity used Latin for both its liturgy and for the Bible, even when local populations had different languages. The Church’s insistence on the use of Latin had the effect of creating a barrier between the clergy and their parishioners (who could not usually understand Latin in its spoken or written form), as well as creating a monopoly on the interpretation of the Bible. Luther’s call for a German-language Bible was seen as a threat to the Church, since it would allow lay people access to the Bible in their own language and break the Church’s monopoly on theological interpretation. If laypersons could read and interpret the Bible on their own, Catholic leaders feared (rightfully so) that the authority of the Church would progressively weaken over time and Christian doctrine would begin to splinter.

Martin Luther is considered the father of the Protestant Reformation. Luther wrote the 95 Theses in order to protest what he regarded as flaws in Catholic doctrine. One of these perceived flaws was the papal bureaucracy acting as an intermediary between God and Man. Luther saw this as unnecessary, as the apostles did not have this when Jesus was alive. Luther also believed many of the priests and friars who served the daily needs of the people were corrupt and did not know Church doctrine.  
Another difference Luther had with the Catholic Church was the selling of indulgences. Luther saw the only way into Heaven was faith in Christ, not buying and selling indulgences. The Catholic Church of the early sixteenth century had a system of indulgences, which meant paying for sins by earthly means. Luther did not see any of this in the New Testament, so he did not want it in his sect of Christianity. He wanted the focus to return to individual prayer and faith.