Stick is fully reusable.

The stick is only planned to be partially resuable.

Planned, yes. However, the simple fact is that the first solid stage is
reusable, while the second stage goes to orbit, leaving large
propellant tanks and the SSME available. The tanks would make a fine
basis for a space station or an upper stage (or a propellant storage
facility, hab modules for the lunar surface, raw materials for SPS, you
name it); the SSME can be cut off and returned. It's only a lack of
even moderate imagination that makes the 2nd stage expendable.