The Users are like the accounts of the gods to Sensei's/The player's database. Nozumu's account is User1 but it's dead and various other beings/angels tend to use it to either narrate, have game shows, or abuse Sensei to feed HOPE who is Nozumu's essence and what Angels ultimately serve.
User2 is the Wire god that doesn't feel and doesn't do much unless given permission or asked to, and seems to be either involved with Tsuneyo or is literally her father. This is the tree and calm god, that can alter perception and memories, etc. It is likely the one that resets the world at Maya's behest, and the one that has the most power in winter.
User3 is Pareidolia, the concerned god, and likely the one who helps and uses only lower case letters most of the time. They are the weakest, but are growing and although not on Sensei's side, are planning on using him for good, or so they say. Doesn't have a season unlike the other two, so it tends to bide it's time.
I could be wrong though, as it's been a while since I replayed.