The practical difference: a psychiatrist is a medical doctor who can diagnose and prescribe medication. A psychologist works through structured conversation and assessment and does not prescribe. Both are legitimate; they do different jobs.
Which you need depends less on how bad you feel and more on what kind of help the situation calls for. Broadly: if you want to examine a pattern, a decision, a relationship or a way of responding, a psychologist is the usual starting point. If your symptoms are severe, came on suddenly, are getting worse, or include things like not eating, not sleeping for extended periods, or thoughts of harming yourself, medical assessment should come first.
Many people end up seeing both, and that is normal rather than a sign that something has gone wrong. Medication and conversation address different parts of the same problem.
Given you say it has been a long time, I would not spend more weeks deciding. The free ten-minute call costs nothing and exists partly for this question. If a psychiatrist is the better fit for you, you should expect to be told that rather than booked in.
This is general information in reply to a public question, not advice about your own situation, and it does not create a client relationship. If you are in immediate danger, contact emergency services.
