In water, O is sp3 hybridized. Due to stronger lone pair-lone pair repulsions than bond pair-bond pair repulsions, the HOH bond angle decreases from 109.5° to 104.5°. Thus water molecule has a bent structure.
H2O2 has a non-planar structure. The O—H bonds are in different planes. Thus, the structure of H2O2 is like an open book.