You might need to define psychiatric rehabilitation, as "rehabilitation" can of course be applied to a whole slew of different areas (e.g., physical, cognitive, substance abuse, sex offender, domestic violence, etc.). However, each of the examples I provided could involve substantial psychotherapeutic components, and may often need to in order to be optimally effective.
So I guess the short answer might be: they aren't necessarily one and the same, but they can overlap substantially.