Decorative, Battlement & Expansion

Decorative

Decorative items are small structures used to increase Public Order. They take up relatively little space and all do basically the same function. The difference being each one you unlock further into the game performs better than the previous ones.

Battlement

The Battlement upgrades refer to the walls your troops use in defense. Upgrading these provide better defense for your wall and gates.

Expansion

Expansions are pretty self-explanatory. They increase the buildable land your castle has. Meaning more room for the many structures you can build.