I'm on edexcel too... C3 was hard at first, but seems really simple after understanding all the trig, and doing C4 Can't stand the C4 "Integration" chapter, a more fitting name would be 'Differentiating backwards and making an educated guess'.
I think core 4 is easier for those with a natural talent in maths as the exam papers always go that one step beyond what is actually taught clearly in order to really distinguish between the good (i.e the people who revised) and the excellent.
well, i'm on the ccea board, and personally i found both easy enough. I feel that c4 is slightly easier than c3, but the exam was harder. Still, i feel i did much better in the c4 exam than the c3.
It was explained to me like this, c3 is easier for the people who revise a lot, even if they aren't as good at maths, whereas c4 is easier for the people with a natural ability in maths, even if they dont revise as much.
I do OCR Maths , and i reckon the C3 exam has more topics to learn so may be harder for some including me but that is offset by the lower grade boundaries whilst C4 is difficult but fewer chapters and i reckon if you know the difficult chapters well enough like Differential Equations and Integration they you are fine