What's the difference between counselling and
psychotherapy?

Counselling is often shorter term and offered for a fixed period of six
or twelve weeks whereas psychotherapy tends to be longer term - often
six months or a year or more.
They both work with similar issues although counselling might focus on
one specific issue, perhaps a relationship breakdown, while
psychotherapy will usually have a wider perspective including all areas
of someone's life as well as how past experience affects the present.
Psychotherapy training is generally longer and requires a deeper
engagement with the process. There is usually a requirement for a
trainee psychotherapist to engage in their own personal therapy
throughout the training period.