Can anyone explain to me in simple enough terms ...

Question

What the difference between a psychologist, a psychiatrist and a psychotherapist is?

Answer 1

A psycologist investigates the mind.

A psychiatrist treats mental disorders.

Answer 2

A psychiatrist is a qualified doctor and therefore can prescribe medication. They can work as psychotherapists too, but their title is psychiatrist because of the years of extra training they have done.

A psychologist is a broad term and covers many things, including eg. researching for industries which colour paint they should use in the toilets to reduce the time their employees spend there.  

A psychotherapist is a counsellor - the only difference is that counselling often refers to client-centred therapy, whereas there are many other types - behaviour therapy, cognitive therapy, gestalt therapy.  Any of these therapists can call themselves counsellor or psychotherapist though and so the words can be interchanged.