SPOILERS!
Well I have looked through some of my posts and even I can't find the answers so I'll just start again, here goes...
Bk1 Obviously massive changes here, extended start and finish you can now save Fogwood, fight Cener Druids, pick up Kai Master's +1CS Weapons (all except Short Sword), use Kai Crystals (magic bombs!), buy armour, fight a Helghast, etc. Of the major changes to the original story you only start with 0-9 Gold Crowns and nothing else, the route to Banedon is radically changed - he is no longer near the monastery and you don't need Sixth Sense* to meet him, the Gourgaz fight now at '387' {previously '255} does not give you the chance to pick up the Prince's Sword and the 'Soldier's' have +1CS Durenese Swords now at 88 {previously normal Swords at '62'}.
*If you use Sixth Sense on leaving the monastery you will NOT get the Fogwood & Ceners section, nor meet Vurnos who may reappear Bks29+...
N.B. Book 1 is now THE hardest book to complete due to limited Disciplines & Equipment and a VERY tough fight when you meet the King... (assuming they will sort out Shamath's riddle Bk16 and Ixiataaga, etc. Bk17 as Joe has promised).
Bk3 '4' Mongoose: Bone Sword +1CS in Kalte only (although this is a Dead End - literally)
{Previously just a Bone Sword}
Bk3 '210' Mongoose: Bone Sword +1CS (anywhere I assume)
{Previously just Bone Sword}
Bk6 '26' Mongoose: Altan CS28 EP50(Target Points). Also the text explains you cannot use a Shield, etc. and Weaponmastery Bow adds +3CS in this instance, not +3 Random Number in Combat.
{Previously Altan CS30 EP50}
Bk6 '252' Mongoose: Silver Oak Bow correction - now carried as a Special Item.
{Previously Silver Oak Bow carried as a Weapon but confusingly treated as a Special Item Bk13+}
Bk8 '183' Mongoose: Gnaag Helghast CS34 EP48. (With Paido's Sword).
{Previously Gnaag Helghast CS32 EP46 - harder now!}
Bk8 '308' Mongoose: Gnaag Helghast CS38 EP48. (With Sommerswerd).
{Previously Gnaag Helghast CS32 EP46 - again harder now.}
Bks 8+ Mongoose state that you may now only carry 50 Coins of any type - Bk 10 even states "A Lune takes up the same space in your Belt Pouch as a Gold Crown even though it is worth only a quarter of a Gold Crown." However Bk 13 sets this straight saying you can carry coins up to 50 Gold Crowns in value in your Belt Pouch. After all 50 Kika = 5 Gold Crowns only!
Bk9 '10' Mongoose: Zakhan Kimah CS30 EP38. (With Dagger of Vashna)
{Previously Zakhan Kimah CS34 EP40 - still better to just throw it!}
Bk9 '128' Mongoose: Zakhan Kimah CS39 EP46. (With Sommerswerd)
{Previously Zakhan Kimah CS44 EP50}
Bk9 '188' Mongoose: Zakhan Kimah CS29 EP38. (With Psychic Ring)
{Previously Zakhan Kimah CS34 EP40 - Ring now better than Dagger}
Bk10 Mongoose: Starting Equipment now includes Potion of Alether +2CS (Yes!)
{Previously not mentioned, even with everthing maxed Bks 9 & 11 practically impossible}
Bk10 '54' Mongoose: Silver Oak Bow does not 'count' as a Special Item Weapon vs Lapillibore AND Tutelarys with Weaponmastery only deduct 2 CS if they have no Speial Item Weapon.
{Previously not mentioned}.
Bk10 '304' Mongoose: Fighting one-handed you cannot use a Shield vs Lapillibore.
{Previously not mentioned}
Bk11 '204' Mongoose: Chaos Master (Badly Wounded) CS38 EP54. (With Ironheart Broadsword)
{Previously Chaos Master (Badly Wounded) CS40 EP58}
Bk11 '270' Shadow Reavers Psychic Combat now states you may claim the +2CS Bonus from the Silver Helm but not from Shield or EP Bonus from Armour. You also cannot claim CS bonus for Alether, Sommerswerd, etc.
{Previously not mentioned}
Bk11 '341' Mongoose: Chaos Master (Lightly Wounded) CS44 EP62. (With Sommerswerd)
{Previously Chaos Master (Lightly Wounded) CS47 EP68}
Bk12 Mongoose: Mini-Adventure informs us a Bronin Vest may not be worn with a Chainmail Waistcoat but can be worn with a Padded Leather Waistcoat (or I assume worn over Kagonite Chainmail instead).
Hope that helps - there probably are other changes but I haven't played the new versions yet just skimmed. I am waiting to get all the books and read them in one big run.
Cheers, Richard.