I dont think I have to even say it again, definitely its harder and One thing is one should not procrastinate studies in A-levels.
I dont remember who but someone said, comparing difficulty of IGCSE and A-level, that an A in IGs is like an E in A-level (Its not a fact but just to compare)
I have seen people who got 8-9 A* in IGs and in A-level they got Cs and Ds
So we definitely have to work harder than we did in IGs.
But as Fidato said if you concentrate its going to be easy
Good Luck