From the Translation about NA 15
1. More than 2000 officers and more cities than NA 14
2. There are two types of solider, one is peasant soldiers, recruiting them will reduce agriculture yield. another is professional soldiers, recruiting them will spend a lot of money.
3. Tons of historical events have been added.
4. The detail of the map is 100 times than NA 14.
5. Because of the the map has more detail, zoom in you will see the battle like NA 14 into battle scene. Zoom out you will see the battle like NA 14 big strategy map. Therefore no more into battle scene.
It like this game: Hegemony III: Clash of the Ancients,
http://store.steampowered.com/app/308173/Hegemony_III_Clash_of_the_Ancients/
You zoom out it shows your troops are many chess move on the big map, when you zoom in it become a RTS battle field.
6. You troops don't need to follow the road. you can let your troops go anywhere. Do not need to build the road like NA 14.
7. NA 15 main system is the "will" system which is improving AI, complex AI. Different clan have different plan. if you or other AI block or interrupt another clan's "will"(plan), this clan will react your action and judge whether or not you or other AI have threat for them. If this clan think your or other AI's actions have threat for his "will"(plan), he will declare war with you or other AI.
From the translation I think the "will" system more like the Civ 6 leaders' opinion system. e.g. When you build a wonder, you interrupt the AI Qin Shihuang's wonder plan. He will dislike you and warn you. If you keep building many wonders, he may be declare war with you.
8. From the AN 15 official website, I can confirm that the NA 15 UI's main color will be dark blue and dark red. other UI's color will be brown and dark green.
9. the game will be released this year(2017) winter time. but because it is a KOEI's game. We all know KOEI = dark and shame. Therefore the release date may delay to 2018