Space/Time is what we experience here on Earth, 3 dimensions of space (horizontal, vertical, and depth) and 1 dimension of time (the one continuous flow of time). Time/Space is what we will experience if we are able to pierce the veil, 3 dimensions of time (past, present, and future) of wherever you are which is the 1 dimension of space (yourself).
To make an example of this imagine an apple. The outside of the apple is the infinite universe which is space/time. The inside of the apple is time/space which is a continuous loop that can be traveled. In order to reach time/space you must be able to pierce the veil and get in to time/space from space/time. Of course I know the apple isn't infinite, but imagine that apple as the infinite universe.