ConfinedOrbitals and HydrogenOrbitals are really quite similar in shape and function. Both have compact support (they go to zero exactly at a certain cut-off radius), and they are both based on solid harmonics for the angular part. The only difference is how we determine the radial part, which in both cases is a numerical tabulated function in the end.

For a ConfinedOrbital we use the pseudo- and core density from the pseudopotential to calculate Hartree and exchange-correlation terms. For a HydrogenOrbital, there is no other density than the one for the single orbital that you are solving for, so the Hartree and exchange-correlation terms are zero and we are left with only a 1/r potential.