To answer the question it is important to understand that although the names sound similar they are really different professions. Psychiatrists are physicians [have a medical doctorate (MD) or doctor of osteopathy DO]. Psychiatrists attend medical school and complete post medical school training for 4 years (general psychiatry) and can do a fellowship afterward to specialize (child and adolescent psychiatry, geriatric psychiatry, addiction psychiatry, consult liasion psychiatry, etc). Psychiatrists prescribe medications to treat mental health conditions and may also do psychotherapy. Psychologists have a PhD or PsyD. PhD programs tend to be research oriented and PsyD programs tend to be more clinically focused. Psychologists provide treatment by performing psychotherapy. Psychologists may also do neuropsychological testing. Organizational psychologists may work in corporate america providing consultation and analysis to improve workplace teams and processes. So, both of the programs are challenging (in different ways). A strong science background, particularly in biology, chemistry and physiology are necessary for medical school (psychiatrists). Strong written, verbal, and interpersonal skills are helpful for both professions, but even more so for psychologists.