That is a good question!
The first group, at the top, is the work of the featured artists. This includes the group that was that the founding artists of DPW (the permanent featured artists), the 15 winners of the previous month's DPW contest, and the Spotlight artist we are currently highlighting at the very top of the website. It is important to explain that the founding artists are permanently featured because of a negotiated agreement that was made with them when DPW opened its membership to all artists.
All the work below that of the featured artists are from the non featured membership and is sorted alphabetically, with a caveat. The caveat is the non featured work is being rotated upward so that, on average, everyone gets exposure at or near the top, right under the featured work, every three hours. This rotation causes the alphabetized block of non featured artists to be split at an ever changing point, which is why you are seeing the two alphabetical blocks of artists.