Hedera helix (common ivy, English ivy, European ivy, or just ivy) is a species of flowering plant in the family Araliaceae, native to most of Europe and western Asia. A rampant, clinging evergreen vine, it is a familiar sight in gardens, waste spaces, on house walls, tree trunks and in wild areas across its native habitat.
Hedera helix is taller than English ivy on average.
It's incorrect because they refer to the same thing. It's difficult because height is never mentioned in the text so the system assumes it must be neither correct/nor incorrect, but this doesn't have to be the case.