So 2D mode is essentially all your entities drawn on a piece of paper. When you pan around the world its really just you moving that piece of paper around. You perspective is essentially the same just your frame of visions moves from one space to another.
3D mode might be a little misleading in that you can’t turn / fly around in the way you might expect to explore this space. For us what 3D mode means the entities are actually plotted along 3D space, they have an X,Y & Z coordinate. Your controls for navigating the space don’t change (its just panning & zooming) however the perspective will change, this means entities further away from you will move slower then entities closer to you when panning (the parallax effect). It’s really just an effect to get an idea for the vertical space of the world. For this reason it makes things like grids difficult to visualise. Hence why they are not present.
I hope that answers your question!