What is the difference between a drama school and stage school?

Answer 1

Theater and drama schools would be the same in the USA. Never heard the term stage school here.

Answer 2

I don't know about other countries, but in the UK the term 'stage school' refers to an establishment run either as a full-time school (including normal classes) or a part-time school for children, teaching acting, singing and dancing.

A drama school is one which teaches the over 18s, after A Levels at college or high school, up to degree standard and many also offer post-grad courses.  Their courses are full-time and very expensive.