The Fairphone 3 comes with this family of modules:

The top module, camera module, and bottom module are all here, much like in the Fairphone 2.

The loudspeaker now gets its own closed module (as opposed to being part of the bottom module), and connects to the rear of the bottom module.

If you hope to upgrade your Fairphone 2 with these modules, we have bad news. Modules and their inner parts are not compatible. But their housings are said to be produced from 50% recycled polycarbonate, so there's at least some reuse!