Nest Thermostat E has got an outstanding sleek white design. The diameter size of the Nest E is 3.19 inches. Also, it's a bit smaller if we compare it to the Nest Thermostat 3rd Gen. While the E has a 320 x 320 resolution and the 3rd Gen has a 480 x 480. The Nest E has got all the loved features like Auto-Schedule, Energy Reports, Auto-Away, Nest Leaf. Moreover, most importantly, it works with Alexa & Google Home. So the main difference or the significant change besides its astounding fresh white design it is now HVAC Compatible. You can control the Nest E from anywhere, and check your energy history, and see if there is a problem. The pretty cool thing is Family Accounts so that everybody can have access to the Nest app. When it comes to saving energy, the Nest E can save us between $131 to $145 a year.