You're missing the point.

Obviously, there is no sharp line. That is too trivial to mention. But the distinction is made, because it captures something about the characteristic spirit of an age.

In the received black legends of whig history, the Renaissance is typically presented as some kind of enlightened rift with and rebellion against the supposedly dark and evil Middle Ages, but in some sense, it is more accurate to view it as a culmination of the Middle Ages or something continuous with it.

You will find great rifts later on with the rise of modernism.