If it was the same, as difficult, they wouldn't have changed it.
I used to teach a couple of friends maths, not professionally, who did the GCSE and I can tell you categorically it's a simpler exam! (Why else would they ar$e with it!)
I did basic Calculus in my O level; it was nowhere to be seen on a GCSE anywhere.
Did you know four out of three people can't even do simple maths?