Mathematics for IGCSE & O level - Mensuration (Section 6 - No. 21)
What is the key difference between a 2D and a 3D shape?
2D shapes have area, 3D shapes have volume
3D shapes are flat, 2D shapes take up space.
2D shapes have volume, 3D shapes have area.
2D shapes are hollow, 3D shapes are solid.
Explication
2D shapes are flat and have area, 3D shapes have depth and volume.