What's the difference between Counselling and Psychotherapy?

The difference between the two is a hotly debated issue.
The British Psychological Society, defines counselling as: "a system intended to help people improve their sense of wellbeing, alleviate their distress, resolve their crises and increase their ability to solve problems and make decisions for themselves."

Psychotherapy may be more helpful for psychological problems that have built up over years.

The British Association for Counselling & Psychotherapy (BACP) definition of counselling:
Counselling and Psychotherapy are umbrella terms that cover a range of talking therapies. They are delivered by trained practitioners who work with people over a short or long term to help them bring about effective change or enhance their wellbeing.

I tend to use the two terms interchangeably and work both short term and long term according to client requirements.