Many people tend to use the terms "Echo" and "Alexa" interchangeably, but even though their functions are deeply intertwined, they're actually quite different things. Amazon Alexa is the artificial intelligence system (kind of like its "rival" Google Assistant) that responds to your questions, acts on your voice commands, and does all the myriad other things that Alexa can do — but we'll get to that in a minute. On the flip side, Echo devices are simply the conduit for bringing that service to you. That's why Echo devices take on so many different forms, from spherical speakers to video screens to earbuds you can take on the go.