Is celta higher than icelt

By no means, no! CELTA is a very practical course for budding teachers whereas ICELT helps experienced teachers deepen their methodological knowledge of teaching in their own contexts. I would recomment teachers take both. Being a tutor of both, I can perceive how much teachers improve the teaching skills after taking the CELTA. After taking the ICELT, they tend to become more aware/critical of what they do. They are both certificates. Delta or an MA TESOL would be the step above.