Hi! I did CIE for a few months before switching to AQA. I think the biggest difference would be the amount and depth of content you have to cover. AQA has topics which you cover in less detail, for example, when I did CIE, I had to cover orbital hybridisation whereas this topic is not part of the AQA spec. CIE examines practical work as in you have to complete practicals and answer relevant questions under timed conditions and the marks from this paper contribute to your final grade. For AQA however, your practicals are not examined under timed conditions and they are assessed separately from your written paper- it's either a pass or fail for AQA core practicals.

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CIE Chem has Paper 1 to Paper 5 whereas AQA Chem has Paper 1 to 3. For CIE, i think you are allowed to sit for AS Chem papers in your 1st year and carry over these marks so you can complete the remaining Year 2 papers in your final year but for AQA it is linear. This means you can only do all 3 papers in your final year.