I realize watching a couple hours of video can be a slog, but what I noticed is that they repeat a couple of rules in other places in the book to remind people (for instance that they can share their gold or give Artifacts to each other), a dotted line is missing in one picture (doesn't impact anything) and there are some names changed, but the rules are identical as far as I could see to the 1990 NA edition.
Before I start rambling here, you may find value in checking out the
Errata discussion.
The short version is the rules are effectively the same. Most of the ambiguities haven't been touched at all in three decades, just re-printed. EU (and Japanese) players would get a shock, because these are the NA rules. They deleted the line about the Wizard being able to buy powerful magical items in future expansions with the gold he saved (he's just advised to be wise and save his money but without an explanation).
What has changed slightly are the cards. I would call these clarifications more than anything, before we get into the new cards that only factor into the new packs.
"The Armory" still exists as a concept between quests but it consists of a deck of Equipment cards. Stock is NOT limited by the number of cards (just for reference). Added to the deck are Holy Water and Potion of Speed (formerly of the EU treasure deck) and the Alchemist Shop Potions as well as Hand Axe and Bracers (EU exclusives) with higher prices than their EU counterparts.
New Artifacts (found only in the new expansions). A non-throwable Spear that attacks with 1 extra attack against dragons; a longsword that lets you re-roll one of the dice 1 time per quest; a crown that let's you see through darkness of any kind plus 1 extra defend die; a ring that raises your BP max by 1; a non-throwable dagger that does 1 unblockable hit per quest but is otherwise normal.
See Cards:
Wand of Magic, Spell Ring (they don't restrict to Elf/Wizard, because there are more heroes who can use magic now, but leaves open possibility of spell scroll users having them).
Borin's Armor: clarifies you can combine with a shield and/or helmet.
Courage - specifically spells out LINE OF SIGHT.
Oddly enough the Spell Scroll version of Courage (2 copies, in each in KK and ROTWL) uses the old wording of "you can see."
The addition of Bracers means the Wizard can have one higher defend dice roll than before. Says can be combined with a helmet and/or shield so not limited to the Wizard either.
The fact they forgot to put "cannot be used by the Wizard" on the Hand Axe, means he gains a new throwing weapon (and a 2 dice attack potentially before he gets the Wizard's Staff artifact).
Regarding the quest books:
There's a Spear mentioned in one of the new expansions but no card for it (so you can just imagine the stats are equal to the EU edition, or fill in whatever you want I suppose).
No instruction is given on how to use the Druid or Warlock, so you can use your imagination or disregard them. There are nine "new" spells between them but two of the spells are just copies of HealBody and Sleep. Each character has the ability to heal themselves (at least), recharge one of their three spells under certain conditions, and have some limitations on gear they can use (Bard's just offers a bonus opportunity, the others its a hard restriction).
Three single unique tiles are present that are given no explanation on what to use them for.
All of the other errors and oddities of the 1990 version of the GS and 1991 versions of KK, ROTWL are pretty much copied verbatim with just a few name changes to avoid triggering GWS.
I haven't gone through every bit of parchment text in the remade quest books, but it seems the biggest change is the Monsters section of the Game System book (half the entries have changed in some way, but STILL doesn't impact gameplay in any way).