The GCE O level is the old equivalent of a general (ordinary) high school diploma in the United Kingdom and many of its territories. The GCE O level has never applied to any of the schools in the USA.
The General Certificate of Education (GCE) Ordinary level suffered problems due to the two-tier nature of the system. Hence, in 1988 it has been replaced General Certificate of Secondary Education.
This was referred to as a general certificate of education used by the United Kingdom and some other countries. This was done away with in favor of the general certificate of secondary education.
GCSEs are the new name for O Levels, which are qualifications taken at 16 years old in the United Kingdom. They're not taken in the USA except in specialist schools.
