: Whoever told you that they were the same thing led you astray. They are only treated : mathematically the same way. Even then there are differences. They are not physically the same thing. Einstein : even stated this outright.

Consider the displacement DI2 between two events occurring along an inertial(for simplicity) observer's world line. In this observers frame the displacement is DI2 = -Dct2

Now consider the displacement as observed by any other inertial frame. It is now DI2 = -Dct'2 + Dx'2

The time displacement for one frame is split into partly a time and partly a space interval between the two events. It is the fact that the space and time components of one frame both mix together to give a purely time displacement of the other coordinate frame that demonstrates some level of sameness between time and space. I agree with Einstein to the point that a world line(time) is never space-like, but this is the limit to our distinguishing of time from space.

• http://hometown.aol.com//zephcochrane/WarpDrives.html