IGCSE vs. O-Level

Hello everyone, this is my first post and I don’t even know if this is the right section to post this in, but, I was just wondering what the differences between IGCSE and O-Levels, both offered by Cambridge International Examinations are, seeing as they both seem quite similar. This is simply for curiosities sake, seeing as I don’t think I would have the option to do either of them. Thanks everyone!

IGCSEs are the international version of the GCSE which is given within the UK. O-levels were replaced by the IGCSE and GCSE (for years 10 and 11 in the English System) as the precursor to the A-levels (for years 12 and 13 for those planning to go to university on the academic track).

Okay thanks, I was just confused because their website gives the impression that O-levels are still being used.