I haven't really sat down to do a long comparison, so this might be obvious stuff to those who have. But what are the essential differences between these retro-clones?
From what I understand:
Labyrinth Lord is Moldvay (or perhaps Holmes) B/X, with AEC as a bolt-on for AD&D-like additions. That's pretty clear to me, and from reading LL adventures it's very clear I need to keep my red box Basic Set hat on to follow it.
But these throw me a bit: White Box is the LBBs. So what exactly is Swords & Wizardry? LBBs plus all of the supplements, or just part of them? Looking at it, it seems very close to both Basic Set and the LBBs. It's hard for me to pick out the real differences between them.
I'm also not really sure how OSRIC fits in here, either.
I'm asking mostly because I use supplements for them for inspiration for my own GURPS 4e game. And because it's easier for me to understand the material if I know which rules assumptions underlay them.
I'm sure I'm embarrassing myself in front of all the OSR folks just by asking these questions. But I think I really have all this stuff already - I have a (battered and colored-with-marker) copy of the Holmes Basic Set. I have both the Moldvay and Mentzger Basic Sets (and most of the follow-on books). I have the actual white box D&D with the LBBs, and Supplements I, II, and III. I have all my 1st edition AD&D stuff. And I downloaded the free copies. It's just hard to read through all four of them in PDF and then track the differences, so I need a better handle on them. I'd like to know what each of them represents, in sort of a Venn diagram of coverage. Maybe I need to sit down and read one or more of them, or maybe I'm good with just grabbing my original stuff off the shelf if I get stuck.
Any pointers to comparisons, explanations, or reviews would be helpful.
(Editing 10/29/11 - I saw this great post on Troll and Flame with a picture reference of system equivalency: Publishers & Products)