Devices within a group do not need to be identical. However, because the group is expected to always stay in sync, those devices will have to share the same lighting capabilities. In other words:

• Lights you want to group need to have access to the same list of light modes
• Lights you want to group need to have the same CCT range (warmest white, coolest white values)

Let's look at a few examples:

• If you want to group two Poles (full color lights, same white range), you can
• If you want to group a tunable white filament bulb and a Hero table lamp, you cannot, since the bulb cannot play color modes
• If you want to group an amber coated filament bulb with a clear one, you cannot, since the two bulbs have different white ranges (the amber-coated one is a warmer light)

There is no limit to the number of devices you can have within a group. There is also no limit to the number of groups you can have per room or per home.