Google sells two models of its smart Nest thermostat \u2014 the 3rd Generation Nest Learning Thermostat and the Nest Thermostat E. While the products seem similar at first glance, there are a few key differences that will help guide your purchasing decision.Nest Learning Thermostat, 3rd GenerationThe standard Nest Learning Thermostat is the more expensive of the two, with a MSRP of $249. The unit itself is 3.3 in. in diameter, surrounded by a polished metal ring that comes in seven colors, allowing you to match it to your interior.This Nest thermostat includes all the functions you’d expect from a smart thermostat, including the ability to learn your family’s habits and create a customized energy-saving schedule. It also enables remote monitoring and control via your smartphone, as well as integrating with other Nest devices and Amazon Alexa.This model has a few additional features that make it stand out. First, the 3rd Gen Nest Learning Thermostat is compatible with 95 percent of 24V heating and cooling systems, more than any other Nest thermostat. It has a high-resolution color display with Farsight technology, meaning it lights up when you enter a room and shows the temperature, weather or time. And it comes with a two-year warranty.Nest Thermostat EThe other model is the Nest Thermostat E, with a MSRP of $169. With this significantly lower price tag you might expect fewer features, but most of the differences are cosmetic. The Nest Thermostat E is slightly smaller at 3.19-in. in diameter, and its body is made of polycarbonate with a ceramic-feel finish. And this model is only available in white, with a less-vibrant “frosted” display that’s supposed to allow it to blend better into any room.Functionally, the Nest Thermostat E has almost all the same options as the Nest Learning Thermostat. The most significant differences: The E only works with 85 percent of 24V heating and cooling systems (it lacks the additional wire terminals of the Nest Learning Thermostat), and it lacks Nest’s Farsight feature. And the warranty is shorter, only one year.One feature only available on the E is an optional pre-generated basic schedule, which the thermostat then builds on as it learns your habits. Otherwise, it has the same learning capabilities as the 3rd Gen Nest Learning Thermostat.Which Model Is Right for You?As you can see, many of the differences between the two Nest thermostat models are external.The Nest Thermostat E is made from lower-quality materials and has fewer color options. But if you’re more concerned with saving money, this lower-priced model has the same key functions as the more expensive option. Just be sure to check the compatibility chart to see if the E will work with your heating and cooling system. If not, you’ll need to upgrade to the 3rd Gen Nest Learning Thermostat.No matter which you choose, you’ll enjoy hands-off heating and cooling, save money on energy, and take advantage of all the core Nest thermostat functions.Check out our guide for how to install a Nest thermostat.