Many people confuse these four terms because there is a bit of each in the other and they intersect in many places. So what is each one and how are they used?
A coach's work revolves around helping clients to achieve their goals and solve their problems. The coach does not provide advice or a how-to. The coach only acts as a guide to help the client find his or her own answers. Coaching can cover many different aspects, from business to life to health and many other areas of life.
A therapist works on helping his or her clients to deal with a troublesome past, process emotions, get in touch with their true identity, and process traumatic events. The therapist achieves that using different modalities, that allow him or her to help the clients come to peace with their past.
A consultant is tasked with solving a specific problem based on his or her expertise. The consultant is usually tasked with the details of the problem and works on acquiring and utilizing resources to solve it.
The trainer works on sharing knowledge on specific topics, based on his expertise and qualifications. The goal is to help the people he is working with gain certain skills and capabilities.