I'd suspect too as Thomas says that what is experienced is a reflection of your own belief system, language, symbols and other means of communication.
My guess is that stuff like the physical appearance of the focus levels and so on can be shared essentially because there's a community of people (e.g. as on this forum) who have read the Monroe books and shared their experiences - whether at this physical level, or at unconscious levels of collective mind.
It can't be by accident that other well established traditions tend to experience estoteric realities specific to their own traditions - for example Buddhdism (in its popular forms, and when teaching at the more basic levels) visualises and anthropmorphises positive and negative beliefs, and indeed higher aspects of mind as Gods (stuff to which we experience attachment) and demons (stuff to which we experience aversion) of various sorts - and that's what people immersed in that tradition tend to experience.
It's a really fundamental issue as i've posted about before in that unless we've managed to transcend ego not only does mind communicate in terms we are familiar with (we wouldn't otherwise understand), we also tend to interpret/perceive what we experience to reinforce our beliefs.
i.e. we find what are very often erroneous beliefs being reinforced because we selectively perceive our experience to reinforce our beliefs.
Which is why this area of experience is so tricky, and so potentially misleading - and why spiritual opening and true seeing result not from ever more intellectually based conceptualisation, but from dropping all of our belief in our ability to see 'truth', and hence to pro-actively act to control and determine an optimum path for our lives.
Its instead taught we should leave it to Spirit, Grace or whatever to tee up the required life experience, insight and intuition.
If we can't do this we end up manifesting what we believe (think we want, what we fear, whatever) anyway - the trouble then though is that it's not what we actually need for us to grow.
That's not to say we should switch off, it actually takes enormous openness, bravery and faith to open in this way and stop fighting what we fear, and chasing that which we think we desire - but the point is that our part of the bargain is to cultivate an appropriate faith, trust and receptivity, as well as the insight required to (even if only retrospectively) see the good as well as the tough bits of this path...
Pardon my using this topic to illustrate a point i've been on about for a while, but i get nervous at the idea that the afterlife is some sort of definitive alternative reality to be explored as an end in itself - our conditioning leaves us very inclined to head down this road...