  Active diffeomorphisms map a differentiable manifold to itself. They
transform manifold points and objects without changing the system of local
coordinates used to represent those objects. What has been called Leibniz
Equivalence is the assertion that, although active diffeomorphisms do change
manifold objects, they do not change what is called the "physical situation"
being modeled by those objects. This paper introduces the contrasting idea of
Newton Equivalence, which asserts that the different values of manifold objects
produced by active diffeomorphisms do model different physical situations. But
due to the assumption of general covariance, these different physical
situations are all equally possible. They represent physically different
situations all of which could happen. This paper compares these two
interpretations of active diffeomorphisms, and comments on their importance in
the substantivalism debate.
