The relationship between these is that the Renaissance and the Reformation can be said to have ended the Middle Ages.
The Renaissance and Reformation ended the Middle Ages by ending the mindset that went along with those times. The Middle Ages were (and this is, of course, a generalization) a time in which people relied on the Church as their only source of authority. They believed what the Church told them about everything from the meaning of the Bible to the way the universe was ordered.
With the Renaissance and Reformation came a major change. The Renaissance, for example, brought an emphasis on science and on scientific proof instead of relying on what religious authorities said. The Reformation, of course, weakened the idea that the Church was the only source of religious knowledge.
In these ways, the Renaissance and Reformation brought in an era in which people did more thinking for themselves. This ended the mindset of the Middle Ages in which they relied on authorities to tell them what was true.