Do psychiatrists have a better knowledge of mental disorders than psychologists ?

Better knowledge depends on your definition. And psychiatrist is a medical doctor and understands and treat mental health through the lens of physical medicine. They prescribe medication and are not the ones to go to for regular talk therapy. They treat symptoms.

A psychologist holds a doctoral degree but is not a medical doctor. They often approach mental health through the lenses of behavior models and development of the mind. They're interested in the 'why." But they also end up running programs, working at universities or concentrating on testing and research. They cannot prescribe meds but can refer you to have meds filled if needed.

Much more common are licensed clinical social workers (LCSW), mental health therapists, addiction and mental health counselors, etc. These are certified or licensed professionals with their feet on the ground of early intervention and treatment. They, too, can refer to a specialist when meds are required, but it's surprisingly rare that meds actually are called for.

Meds can never fix, only mask. They can make life literally bearable for some, but many more might find with a little hard work they can accomplish the same thing, only much more lasting. Find someone with whom you can relate, can share, feel safe with. Whatever meds you need will be available to you.

Psychiatrists are more equipped to deal with people who have abnormal mental health disorders where medication‘s are involved and/or clients with a background of trauma.

Psychologists tend to be more focused on research than actual counseling services

Most if not all mental health issues require medications. Psychiatrists went to med school , did a residency, and can prescribe meds. I believe they are more capable of helping patients with mental health problems.

The ones I know do, as MDs they have a better understanding of biological causes for certain illnesses.