A:Answer There are indeed a lot of Nest products on the market.
The Nest thermostat is for controlling your HVAC, to replace your old "dumb" thermostat. The Nest thermostat connects to your wifi if you want it to be controlled from your phone, laptop, or voice assistants like Amazon Alexa, but it doesn't have to connect to wifi if you just want basic thermostat functions (but why would you not utilize that value).
The Nest connect is for extending the range of Nest secure devices, which are motion detectors and open/close sensors that you can put on windows, doors, etc to protect your home. It's a lot like an ADT-style home security system, but DIY and doesn't require wires as it's all WiFi and battery operated. When those devices are too far away from the central hub (the Nest guard), the Nest connect helps extend range to widen the coverage and make those devices work better.
The Nest camera are for recording video around the house (inside or outside).
The Nest door cam is a doorbell with a camera.
