1.) The Shop Build system is definitely gone. Each shop has a unique inventory now.
2.) The Special Order system doesn't really seem any different from Vesperia's Item Synthesis system aside from ordering stuff instead of having it made then and there (I think you get it immediately either way though). You can get accessories, new absorber jewels, weapons, items, food, and probably some other stuff from it.
3.) Building on the Food thing, it looks like you can order food. The food works like it did in Xillia 1, you get it, eat it, and the effect lasts for a certain number of battles. Not totally clear yet how it will work though, so I'm not sure if you get all food special ordered with certain ingredients, or if you make the basic recipes and use those to order better ones. Seems like you'll have to order it all.
4.) Random Treasures are still around on the fields. You can get items and Elemental Cores and such from them.
5.) The game goes back to a traditional leveling system. You get experience, level up, and your stats increase through that.
6.) The Orb system is more clear now:
* There are six elements altogether on the orb: Fire, Water, Wind, Earth, Light, and Darkness.
* To learn the skills and artes under an element, you equip the Absorber Jewel necessary for it. So if Ludger wants to learn the skill "Stamina", you equip him with the Water Jewel to get water energy, and once he earns 50 points towards water, he'll learn it.
* There are skills/artes between two Elemental Lines, that require points from two elements. I mentioned the Rapid Range arte before, which needs 230 Fire points and 230 Wind points.
* Some Jewels will absorb energy from more than one element.
* The amount of energy absorbed from a single Elemental Core depends on the Absorber Jewel equipped. So the Fire Jewel absorbs 1 Fire point from each E. Core, while the Fierce Fire Jewel absorbs 3 Fire Points.
7.) It looks like they got another idea from Graces, as Artes can be strengthened and given additional effects by relearning them through the Orb system. Additional effects include things like increased power, increased chance to stun enemies, and a chance of the arte consuming 0 AC.
8.) The skills system has been changed. At its base it works like most recent Tales games: you get skills, then equip them based on the amount of SP you have. Then from there it changes. First of all, you don't get SP through leveling up or from the orb. Instead, when you learn a skill, you're given half of the SP necessary to equip it (so if you learn a skill that needs 2 SP, your maximum SP increases by 1). This makes it mathematically impossible to equip every skill, which ties into the second new mechanic introduced. You can also increase your max SP by defeating enemies. Once you defeat a certain number of an enemy, a character in the party will gain additional SP.