Removed:
1) Not so much removed as changed, but Hybrid skills and "maturation" status are gone...however these skills have simply been moved to various human and monster classes.
Added:
1) Lithograph system, which functions like the Grotto system of DQ9, and contained within can be mini medals, various weapons and armour of extreme rarity, rare monsters, special maps that are good for making money or experience farming.
2) Secret extra bonus dungeon I can find NO specific info on how to access, where it's located, what its purpose is, or if there is/isn't a new boss.
3) A secret character...Kiefer rejoins in the post game...however I have no idea how this works, how to trigger it, and most details even on wiki's that mention it are sketchy at best.
4) New weapons and armour (not much, it's like 5-7 pieces all told between weapons/armour/accessories, and almost entirely in fun, with a few useful end-game pieces like a new Hela's hammer that has a higher bonus to critical hits and a higher base damage). The vast majority of this new equipment is exclusive to the Lithograph system.
Changed:
1) Monster park functions as the gateway for the Lithograph system.
2) Monster hearts (rumour, speculation, no proof), can be dropped before the Monster Park opens.
3) Human classes have had their job point requirements cut by 1/2 to 1/3 depending.
4) Roughly 1/2 of all skills and spells are now only usable with the classes they were learned in. This holds true for Human classes (I have seen no confirmation on monster classes). Most to all (not positive) of human skills/spells that are fixed to a particular class, can become universally usable if relearned by a monster class that knows the same skill. So if you want your skills/spells universally useful, gotta ca..I mean learn all of them monster classes. The monster classes are the same as before, as are the tiers, so just farm the base hearts.
5) Monster classes have virtually all of their empty spaces filled out with skills, making them ever more useful to level up.
6) Battles take place in standard 1st person when actions are being selected, and switches to a 3rd person isometric view that shifts the camera depending on the action to make it more cinematic. Very different cinematic feel than 8's and 9's camera movement.
7) Many shops have been altered and "rebalanced".
8) Enemies have fluid and constant battle animations. As well both human and enemy models are 3D.
9) The world map/boat/flying maps are more in line with the DQ8 and 9 changes. And like DQ9, enemies appear on screen.
10) Human classes now have their own special models that show up in battle, towns/castles, dungeons, and on the field. These are unlocked the moment a character takes up a particular class. Ala DQ3 original! As far as I know, character models cannot be altered by changing equipment like in DQ9 and with some costumes in DQ8.
11) Township was altered and streamlined to be more like DQ4's remake.
12) Casino games were slightly altered, like with all DQ remakes, especially slots, which are apparently still forgiving and token happy, but not as much as they were.
13) Some minor tweaks to certain armour resistance bonuses...very minor, a +5 here, a -5 there....stuff like that.
14) The beginning was streamlined, as with all DQ's, especially 6's remake. Sadly, this means the puzzle elements of the Temple are either removed or dumbed down to such a point as to be...well, subtle puzzle-look-alikes.
...that's all that comes to mind. I know there are a few other changes and additions. Nothing was really removed though, that I know of anyway.
Life can be unexpected. Embrace and prepare for anything.
Searchable public mass Declassification, Project Apario: https://projectapario.com/