Well they seem to differentiate between 'plane' and 'density'. They say there is a 3D time/space and space/time, as well as a 4D space/time and time/space and the same for all the densities. So maybe you could say planes are 'horizontal' structures in consciousness and 'densities' are 'vertical' structures in consciousness, if that makes sense?
Although in this quote they seem to refer to planes as being a subset of the density which makes sense if they are the horizontal 'steps' of a vertical structure in consciousness.
Quote:17.38 Questioner: Well, does each… does… this is difficult. Our physical plane: Are there seven sub-planes to what we call our physical plane here?
Ra: I am Ra. You are correct. This is difficult to understand. There are an infinite number of planes. In your particular space/time continuum distortion there are seven sub-planes of mind/body/spirit complexes. You will discover the vibrational nature of these seven planes as you pass through your experiential distortions, meeting other-selves of the various levels which correspond to the energy influx centers of the physical vehicle.
The invisible, or inner, third-density planes are inhabited by those who are not of body complex natures such as yours; that is, they do not collect about their spirit/mind complexes a chemical body. Nevertheless these entities are divided in what you may call an artificial dream within a dream into various levels. In the upper levels, desire to communicate knowledge back down to the outer planes of existence becomes less, due to the intensive learn/teaching which occurs upon these levels.
Although in this quote they seem to refer to planes as being a subset of the density which makes sense if they are the horizontal 'steps' of a vertical structure in consciousness.