Symbols - What does heaven look like
The difference lies in the fact that we are within the tunnel being moved as opposed to moving through the tunnel, implying some degree of help from the spirit world in moving and navigating round the spiritual realm.
Symbolically a plane is a means of transport you cannot control. It leaves from one destination and travels to another destination and may not stop en route. Thus if you have any experience in which planes figure prominently, you are not in control of your spiritual journey, a spirit helper is in control of your destiny .
Unlike a train, the plane travels at Air level.