Which is harder, IB or IGCSE? Is IB too tough as mentioned by many people who have studied it?

The IB and IGCSE are for different education levels, hence it would not be a fair comparison to make. The IGCSE is for 9th and 10th grade, whereas the IBDP is for 11th and 12th grade. However, generally, the IB curriculum is much harder than IGCSE.