Here is a quick break down of products:
((feel free to link to this and added corrections/changes with additional posts))
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Core Set = basic players info, basic gm info, basic player bits, basic gm bits + dice x3, sample adventure
GM Toolkit = extra Gm info, bad guy party sheets, extra basic GM bits (+dice x1?)
Adventurer's Tollkit = more player careers, player bits for new careers, extra basic player bits
Winds of Magic = GM rules for corruption, fluff for magic, more magic like careers, more magic options, bits for new magic, adventure
Signs of Faith = GM rules for disease, fluff for faiths, more priest like careers, more priest options, bits for new faith stuff, adventure
GM Guide = basic GM info (core set), GM rules for corruption, GM Rules for disease, less fluff for faith/magic, sample adventure (core set), better explanation of rules/errata, no bits rules
GM Vault = basic GM bits (core set only) + dice x1
Player's Guide = Basic players info (core set), extra careers (Adventurer's toolkit), extra careers (Winds of Magic), extra careers (Signs of Faith), better explanation of rules/errata, no bits rules
Player's Vault = basic player's bits (core set only) - ((does not include player bits from Adventurer's Toolkit, Winds of Magic, Signs of Faith))
Creauture's Guide = Beastiary, new bad guys, gathers most bad guys from other supplements
Creature's Vault = cards for bad guys (and bad guy actions) in Creature's Guide, plus cards for creatures in previous adventure/supplements
The Witch's Song = New magic options and careers, new magic bits, new creatures, adventure ((none of this is anywhere else))
FULL ADVENTURES
The Gathering Storm (no new careers, has misc. bits)
The Egde of Night (no new careers, has misc. bits)
The Witch's Song (see above)