They all are different. We will put a description of the bristles under every brushette and that's how technically they should be interpreted.
Usually in the toothbrush industry bristles come in 3 different stiffnesses:
However we figured that even the soft bristles are not suitable for every purpose. Some people are used to brush their gum and because electric toothbrushes don't allow easy control of the pressure they have to step back to manual brushing for their gum. To address this problem Brushette® tapped into the makeup industry for even softer bristles: