Well obviously the site is devoted to Christocentric (or Christian) universalism instead of pluralistic universalism. (I suppose someone could be Christian in various ways while still believing all or anyway more than one religion to be equally true, so maybe “Christocentric” universalism would be better as a distinction.)
After that, a big category distinction would be universalists who expect at least some punishment from God post-mortem (purgatorial universalism being a handy term for that concept) and universalists who don’t expect punishment from God post-mortem (ultra-universalism being a handy term for that. Each term is nifty and not derogatory, too. ) Ultra-u’s could still expect some punishment of sinners by God before death–I’ve seen at least one or two examples of that here on the forum in the past–but in my experience most don’t expect any further punishment from God (after the crucifixion or after the fall of the Temple), or don’t expect any punishment from God at all ever (for anyone other than Christ, or not for Him either.) So some ultra-universalists are more ultra than others.
Relatedly, not all purga-u’s quite agree on how purgatory works. Some of us regard it as a threatened real possibility but not as a certainty; others as a prophetic certainty for some people but not for others; others of us regard it as being true (in this or that way) for everyone (I tend to go this route: everyone is salted by the unquenchable fire of Gehenna, but it’s only a punishment to those who aren’t cooperating with the Fire yet). I’ve seen purga-u’s who regard it as being variably intense (which is also my position), and others who regard it as being invariably intense. I’ve seen those (myself included) who regard it as being variably long-lasting depending on the person’s attitude to what’s going on; and others who cipher out distinctions and even exact year counts as to how long various types of sinners will be in the lake of fire. (Stonehouse is a notorious example of that; although he was influential in many ways, his system was not adopted in any surviving subsequent work.)
Cutting across both basic types of Christian universalist are questions of pretty much every other kind of theological topic!
1.) Patrology, Christology and Pneumatology: is orthodox trinitarian theism true, or some other theism; and if some other theism, how do the Son and the Spirit relate to the Father? (The creators of the site intended to focus on ortho-trin, and they’ve chosen guest authors and admins who are usually consonant with that, compared to Tentmaker for example which tends to trend more unitarian.)
2.) Free will vs. determinism, in various degrees and combinations.
3.) Atonement theory: is penal substitutionary atonement true, or some variety of it, or some other atonement theory, or theories?
4.) Eschatology: is preterism true, and if so to what extent, or to what extent is the kingdom of God still on the way and how will God act to bring it about (and if so in what stages of progression if any)?
5.) Bibliology: is the canon opened or closed? Protestant or Catholic canon? Eastern Syrian or Western Syrian canon? What kind or kinds of inspiration do the scriptures have? Is inspiration still active today in an authoritative way or ways (and if so, what relation does that authority have to the scriptures)? How historically accurate are the scriptures? How spiritually accurate are the scriptures?! (i.e. could a writer be promoting a false spiritual idea that we ought to reject and if so on what grounds? Not to be confused with the observation that various characters in narrative, whether parabolic or historical, sometimes get the wrong idea about things!–but then, what if those characters are meant to be authoritative themselves in some way? Do all authors and/or authoritative characters in scripture have what amounts to papal infallibility, and if so what does that involve?)
6.) Ecclesiology: what kind of shape should “the church” have? What kind of authority structure if any? No church groups per se? Strong ecclesial authorities? Papal or multiple top authorities? Variant degrees or combinations thereof? How best should worship proceed?–for everyone in the ecclesia and/or for specific groups and/or for individuals? Should there be creeds to profess?
I’ve personally seen examples of each of those positions (in various combinations) among Christian universalists; and in theory I think purga- and ultra-universalists could each hold any of those options, even though in practice there are sometimes majorities. (Most ultra-u’s in my experience are preteristic to some strong extent for example, which makes sense since the two concepts tend to more easily fit logically together.)
God knows I wouldn’t want to be the one trying to come up with labels for all the variations…