Yes, theoretical chemistry is best described as a subset of Physical Chemistry.
A theoretical chemist will learn and know just as much about quantum chemistry as a physical chemist, in many cases even more. Same can be said true for all the interactions of the various forces, particles, etc.
A theoretical chemist will have little exposure to instrumentation and instrumental techniques such as xrd, nmr, ir, epr, etc etc. That is why there are a lot fewer jobs for them. Conversely, physical chemist will not really have much exposure to the modeling/calculation aspect that theoretical chemist will have.