Any evidence-based insight into any diff in GCSE vs iGCSEs?

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This has probably been discussed before - if so please can someone post the link.

I am keen to understand if there is any difference and any evidence-based info to support this.

Just trying to get ahead as if there is a difference - I am a bit concerned that my son may not bet back into his 6th for as he has done all iGCSEs and needs grade As in his A level selection - whereas offers to new kids joining the school are also A grades for iGCSE or GCSE.

WARNING: New to all this and don't want a bun fight or to be flamed - so if I have said something tactless just inform me!

My DD's school do IGCSE for sciences and maths. Think they need a B grade to progress to A Level. The reasoning is that the IGCSE is better preparation for A Level. I have no idea as to whether this is true!

As far as I know there is no conclusive evidence, only 'perceptions' of differences in difficulties. Science IGCSEs through Cambridge exam board (CIE) are thought to be more difficult than GCSEs, but prepare students much better for A-levels. So schools with a high proportion of students going on to study science at A-levels prefer those. I have heard that English IGCSE, on the other hand, is not as well respected as GCSE -- because it's international, many who take it are second-language speakers and the level is not as high. I have no insight into any other subjects.

The previous poster is incorrect about iGCSE English language. The paper taken by UK based students would be entitled English (first language). I have seen the papers and they are definitely equivalent to GCSE in terms of difficulty.
For Science the papers would be taken by students in a variety of countries so to adjust for this questions may be written in clearer English and wouldn't contain references to everyday life in the UK. For example in GCSE Physics there may be a question requiring students to label the wires in a 3-pin plug but this wouldn't be included at iGCSE as other countries don't use this system. The questions are more traditional in their layout and some require more writing which may be why some schools consider them as better preparation for A level.
The main difference for iGCSE Sciences is that there are no Science ISAs (assessed practical work). A level Sciences do require practical work however so I would ask the school how they cover experimental work so that they have done enough to cope with the transition to A level.

My understanding is that IGCSEs are easier to pass, but the grade boudaries are higher so it is harder to get an A*.

Perhaps look at the grade boundaries OP?