1st to 4th generation: these are the differences of Hue lamps & sets - Hueblog.com
Philips Hue White and Color Ambiance 2nd Generation Smart Bulb Starter Kit (Older Model 3 A19 Bulbs and 1 Hub Works with Alexa Apple HomeKit and Google Assistant) - Amazon.com
Review: Philips Hue White & Color LED Bulb (3rd Generation - 2016) - YouTube