IGCSEs are an international version of the GCSE. To some extent, it does matter whether you buy GCSE revision guides instead of IGCSE- as well as the type of GCSE, the exam board also matters.
Some IGCSEs are completely different from their counterparts, some including a variety of different sub-topics and practical assessment. Likewise, some IGCSEs have a coursework element to them which almost all GCSEs no longer have.
TL;DR - IGCSE is an international [equivalent] version of GCSE. In some cases, it matters a lot as to which revision guide; you should buy a revision guide that is specific to IGCSE and your exam board.