Well, it's worth noting that the pic on the right is a little speculative. Physicists are still working on the whole dark matter issue, and it's a computer simulation.
ANyway, in a way, it's both a pattern
and a coincidence. There are lots of patterns that you see all over nature that are the products of basic math and so on. Here, it's interesting that they look alike because we're dealing with such massively different scales and very different forces. But I can think of a lot of things that look similar. For example, road maps look like this, with nodes at the big cities and webs of roads. Ants are the same way - a big field with a lot of ant mounds would look similar from above, with nodes at the ant mounds and connecting fibers for the ant paths.
It's really a beautiful thing - any kind of self-similarity in nature or the man-made world is cool. It fills me with a sense of awe and humility.
http://www.google.com/maps?f=q&hl=en&q=atlanta,+ga&ie=UTF8&om=1&z=9&ll=3 3.671783,-84.256897&spn=1.615996,3.47168&iwloc=addr