At CNET, we've been testing smart thermostats for years, so it's always a little surprising to hear, "What's a smart thermostat?" But only a fraction of American households, around 17%, actually use smart thermostats. That's too bad, because they're one of my favorite smart home innovations, and offer handy advantages for almost everyone. 

So, what's the difference, aside from flashy new touchscreen designs? I'll take you through what's new with these thermostats and how your heating and cooling will never be the same (neither will your energy bills).

Scheduled heating and cooling

Both smart and traditional thermostats have programmable settings, letting you set temperature thresholds for specific hours and specific days of the week, and changing them as seasons change. The biggest difference is that smart thermostats make this much easier.

With old programmable thermostats, you're mostly stuck doing programming with the thermostats' manual controls. Smart thermostats allow you to set schedules from the app, no matter where you are, and you can usually save and switch between schedules on the fly, making the process significantly smoother.

Read more: Don't Put Your Thermostat In These Places

Costs 

You can find a standard programmable thermostat without any bells and whistles for under $20 from brands like Honeywell Home (although those with fancy touchscreens will cost more), so they're an easy way to save money if you need a replacement. Smart thermostats, with all their added features, cost significantly more. Amazon has one of the cheapest for under $100, but for something like Nest's 4th-gen Learning Thermostat, you'll have to pay close to $300.

Energy savings

Programmable thermostats will save you money, as long as you stay within strict temperature settings at certain times of day and night. Smart thermostats don't necessarily save more, but they make saving money so much easier that houses tend to save more as a result, since very few users have time to constantly adjust a standard thermostat for maximum savings.

With settings like eco modes and monthly reports on energy savings, smart thermostats tend to save the average household significant amounts of money. Google Nest studies have estimated the average user saves around 15% on energy bills annually, while Ecobee says users can save up to 26% at the high end. That's easily enough to cover the initial costs of a smart thermostat in a year or two.

Remote operation

A regular thermostat doesn't have app connections and will, at most, have a remote control you can use from across the house. Smart thermostats, meanwhile, have Wi-Fi connections and apps. That means that as long as you have your phone and a connection, you can make thermostat changes.

For some people, this is an important feature -- they can adjust the temperature while on vacation or if they forget while away from home. Others are fine making changes only when they're at home.

Automatic learning and adjusting

A regular thermostat will heat or cool your home exactly when and how you tell it to. So will a smart thermostat -- unless you enable its smarter features. Smart thermostats include learning algorithms and sensors that study activity in the house, like when people get up in the morning and start moving around.

With basic data like this, smart thermostats can start making adjustments about when to raise the heat or start cooling off, and when to hold back because there's no one at home. Essentially, they can schedule themselves and respond to significant changes in habits.

Also, many new smart thermostats come with satellite sensors that you can place in specific rooms that traditional thermostats may not be able to "read" very well, increasing their temp-sensing accuracy. 

Energy savings

Programmable thermostats will save you money, as long as you stay within strict temperature settings at certain times of day and night. Smart thermostats don't necessarily save more, but they make saving money so much easier that houses tend to save more as a result, since very few users have time to constantly adjust a standard thermostat for maximum savings.

With settings like eco modes and monthly reports on energy savings, smart thermostats tend to save the average household significant amounts of money. Google Nest studies have estimated the average user saves around 15% on energy bills annually, while Ecobee says users can save up to 26% at the high end. That's easily enough to cover the initial costs of a smart thermostat in a year or two.

Installation

Both smart and standard thermostats are installed the same way -- by connecting various wires to the thermostat's base plate. Both offer professional installation services as well, so there's not much difference here.

The biggest difference is that smart thermostats won't work as well with every home system. For example, smart thermostats won't make a huge difference if you use radiant floor heating as your primary heat source (it's slower to respond and doesn't affect thermostat sensors the same way), so you may as well save money with a simpler thermostat.

Connections to other devices

Smart thermostats can often connect to other smart home technology, including security hubs and customized triggers, through platforms like IFTTT or Controller for HomeKit. Since smart thermostats tend to have extra sensors for humidity or air quality, they can trigger things like air purifiers, fans, dehumidifiers and more. Some smart thermostats even come with built-in voice assistants, while most at least support voice assistant control through Alexa, Google's voice assistant and more.

Regular thermostats don't have any of these connections, so you can't usually connect them to home routines or set temperature triggers for other devices.

Bottom line

Smart thermostats make saving money much easier than regular thermostats and come with plenty of extra bells and whistles, including opportunities to connect them to voice assistants and other smart home devices. They're also sleek, smart devices that display personalized info about your home and weather, while learning your habits and automatically adjusting heating or cooling -- no micromanagement needed. Plus, unlike regular thermostats, you can control them from anywhere.

In return, the big drawback of smart thermostats is that they cost a whole lot more than a regular thermostat replacement would, although they do tend to pay for themselves within a year or two. However, not everyone is comfortable using an app for scheduling or letting a smart thermostat make changes itself, so some users may find themselves uncomfortable with the change.

Ready to learn even more? See our guide on the best settings to use on your smart thermostat for the season, the easiest steps to save on heating and cooling bills, and the best smart home devices overall.