More of a difference as to which scale is more lasting. the shells of Diatoms are many millenia old and enduring, the pyramids are several and decaying, while cities and large concrete structures may be large, but they are more ephemeral. The rigidity of the design, vs adaptability, is where the problem lies. Concrete isn't even designed to be permanent, therefor it doesn't last. The pharaohs built for their vision of eternity and it has endured, but the diatoms lived brief spans and their shells endure. The larger and more complicated, the less permanent, while simpler forms are more enduring.
Concrete relies on water, structurally. Geopolymer uses water, but water isn't part of the structure. I need better supplies and better work space, but the difference is like mud and pottery. Fired pottery is not water soluble, yet, before being fired, it is essentially mud (and called that). The reactions within geopolymer are equivalent to pottery firing, in that they initially use water, but water is not a structural member, within the final product, nor is the final product water soluble.