Psychologist or Social Worker which is in demand?

You can earn a decent living with both, but highly unlikely that there will be any overtime as you would be an exempt employee. And, if you have your own practice, that has to be managed by the number of hours you will work in a day. Psychologist requires a PhD, whereas a Master's Degree will allow you to become an LCSW, so lower cost of entry for a salary that is in a similar range. It depends upon what you want to do, since both psychologists and LCSWs can be therapists, but if you want to teach, a PhD, and PsyD/PhD to reach higher levels of practice in the field.