In block empire you will have the ability to design each and every building in the game.
Now being able to design your own buildings is purely optional. You can play fully using all pre-designed buildings. However, design mode makes it possible to completely customize the look of your nation. You can create buildings from scratch or edit pre-existing templates. You can also have as many different designs of buildings as you want for each type of building. So you could design 10 different style of houses and when your workers come to building a house you will be able to select from any one them.
Now building with different materials will effect the building. For example building with strong materials will mean that your buildings are more resilient to damage, however stronger materials will take longer to build with meaning that even though your buildings are nice and strong they will take a long time to build. Likewise building with weaker materials will mean that your building can be destroyed more easily, but you will be able to build them very quickly.
This mechanic will give you a varied strategy depending on how far along in the game you are.