When you take triple science you take 9 exams in total. If you take additional science, you take 6. Core science and additional science are 2 GCSEs. Triple science means you get a GCSE in each Biology, Physics and Chemistry. So if you take additional, you get 2 GCSES. If you take triple, you get 5 GCSES. And yes, it's definitely more difficult as you're learning a lot more new content.