One: you can be trained to see things you would ordinarily not see. It is not that they are invisible, but that you either do not notice them, or do not understand them. For instance, a tracker and everyone else might see the same marks in the sand, but the tracker, through training and practice, can tell almost instantly what the marks mean: a coyote chasing a rabbit that evades it at the last minute, sending the coyote over on its side. Or a botanist will notice the small seedlings of American Chestnut that another will either only see as a patch of green or will not notice at all. We encounter such things all the time, and we are amazed at the perception of the specialist and maybe come to see things a little better ourselves. In this we realize that our perception is limited, and apparently without limit, even though ordinary reality does not change.
Two: between two people, nothing else is noticed, no thing is better understood on the surface; but the same thing seen by one person is understood in some deeper capacity, or to carry much more meaning. However, that meaning cannot be taught in a mechanical way because it has little to do with mechanical reality. Rather, a tree (for instance) is seen as a striking example of an eternal reality even though the perceiver cannot point to anything that would convince another of what he sees. This might seem far-fetched to some, but we experience it all the time on a more limited level: one person might grasp the beauty of a fish's scales shining in the sun, while another person sees all the colors and light but does not understand the beauty. Beauty in this case is a doorway to that eternal reality - the ideal of beauty - and cannot directly be taught, although through personal expression it might help another to open up to the possibility.
Both of the above are examples of simple but profound differences of perception that do not require a PhD in philosophy to understand. Both lead to profound implications for perception, and from there, on how our world might be deeply altered without altering a single material thing. A certain fluke of an understanding on mathematics might lead to the possibility of nuclear power; and a similar fluke on the presence of being might lead to an entirely different social or even world order, all by a shift of perception. FK