honestly there is very little to no difference between them (material-wise), I also did igcses and I think the only difference is that I didn't do any coursework (except for normal GCSE Art), but the syllabus and all for most of the subjects are pretty much identical (I think), but igcses are considered harder in exams.
(P.S What subjects are you doing? I think i've still got some online revision guides for IGCSE if you need them)
I am not sure if ythis will help at all, but in french or german igcse the paper caters for all grades, so it'll be fairly easy with a difficult long question at the end, but generally i think that the igcse's are supposed to be harder. I am doing iGCSE's in french, german, and IT next year.