Leaf Nature is a splash-proof product so it can handle sweat during workout and a small amount of water won't hurt it. However, it is not a water-resistant or waterproof product so it should not be worn in the shower, bath or pool.
Leaf Urban is water resistant and has a resistance rating of IPX6. This means you can wear it in the shower or washing the dishes. It is sweat-proof, rain-proof and can withstand short immersions in water. It is made to withstand exposure to water you might come across in everyday life, but it is not built for diving or intentional swimming.