You can visibly see a difference between the two sides if looking at the core (under the hybrid cover and the mattress inner cover). The firmer infant side has a thicker top layer, while the softer toddler side is slightly thinner. Also, if you squeeze the top layers, the thicker infant side layer is firmer to touch than the thinner toddler side layer.
**Another tip is that the side that has the “Pure” label on it is the softer toddler side:
