What it says on the tin. The Scanner simply give you blueprints, leaving the fragment behind, and the Recycler breaks down fragments. More complex fragments don't give you completed advanced components (like wiring kit etc), but there's a chance you'll get the ingredients of those components (silver, quartz). Or, given how advanced the technology is, you could make it capable of recovering everything, but I think that would break balance.
Might also want to consider an upgrade for the Recycler, or a separate industrial recycler, that allows breaking down of structural wreck components like the spars handing around from the Aurora... but I think those are technically part of the terrain, so I don't know if that's feasible.
Might also want to consider an upgrade for the Recycler, or a separate industrial recycler, that allows breaking down of structural wreck components like the spars handing around from the Aurora... but I think those are technically part of the terrain, so I don't know if that's feasible.