But the main thing that’s different about time is that it has a clear direction whereas the space dimensions don’t. This is caused by the fact that the universe started out in a very low-entropy state, and since then has been evolving into higher entropy. I don’t know if it’s even possible to answer the question of why the universe started out the way it did—it’s almost like asking why anything exists at all. But whatever the reason, the universe is very uniform in its space dimensions, but very non-uniform in its time dimension.
But the main thing that’s different about time is that it has a clear direction whereas the space dimensions don’t. This is caused by the fact that the universe started out in a very low-entropy state, and since then has been evolving into higher entropy. I don’t know if it’s even possible to answer the question of why the universe started out the way it did—it’s almost like asking why anything exists at all. But whatever the reason, the universe is very uniform in its space dimensions, but very non-uniform in its time dimension.