The original Amazon Echo lineup of tiered-speaker heights reminded us of Starbucks coffee sizes (grande, venti, and trenta), but now, it's added a fourth Echo device to the mix.

And it has a radically different design and purpose.

Amazon makes a cylindrical, internet-connected speaker called Echo, which doubles as a personal, cloud-based assistant, addressed as Alexa. It launched in the US in 2015, and it launched into Europe and the UK in autumn 2016. Alongside Echo, Amazon also offers two sibling speakers that debuted in March 2016 in the US, called Amazon Tap and Echo Dot, the latter of which has now been replaced with a refreshed model.

Fast forward a year, and Amazon has expanded the Echo line again. It includes a hands-free camera called Echo Look. The differences between these Echos aren't limited to height, as each one is suited to a specific environment - whether at home, on the go, as an enhancement to your audio setup, or if you want to take photos of your outfits.

Confused about what we mean? No worries. We've dissected how each Amazon device is unique and laid out all the details below.

Release date: 2015 in US, 2016 in UK.
Availability: Available in the US (Amazon US order page) / Available in UK (Amazon UK order page)
Price: $179 / £149
Dimensions: 235 mm x 83.5 mm x 83.5 mm
Weight: 1045 grams
Connectivity: Bluetooth and dual-band, dual-antenna Wi-Fi (MIMO)
Power: Plugs into a wall outlet
Audio: 360-degree sound (2.5 inch woofer and 2.0 inch tweeter)
Alexa: Yes (Always-on/always-listening/voice-activated)

Amazon Echo is a 9.25-inch-tall cylinder speaker with a 7-piece microphone array. It responds to the wake word "Alexa" and is capable of voice interaction, controlling compatible smarthome devices, music playback from smart devices over Bluetooth, making to-do lists, setting alarms, streaming podcasts, playing audiobooks, reading PDFs, providing weather forecasts, warning you of traffic conditions, answering trivia, and supplying other types of information in real-time.

Echo requires a Wi-Fi connection in order to respond to voice commands and fetch content for you, and it must remain plugged in for power. Users in the US will see Alexa have an American accent, while UK users will hear a British accent.

Release date: 31 March 2016 for US
Availability: Available in the US (Amazon US order page)
Price: $129.99
Dimensions: 59 mm x 66 mm x 66 mm
Weight: 470 grams
Connectivity: Bluetooth and supports 802.11b, 802.11g, or 802.11n Wi-Fi
Power: Relies on a charging cradle (9 hours of playback)
Audio: 360-degree sound (dual 1.5-inch drivers and dual passive radiators)
Alexa: Yes (Not always-listening by default; Must touch mic button to access Alexa or enable hands-free option in Settings)

Amazon Tap is a 6.2-inch-tall cylinder speaker with a 7-piece microphone array. So it's a smaller, more portable, more affordable version of Echo, and it comes with full access to Alexa. Unlike the Echo, the Amazon Tap is wireless and must use the included cradle to charge.

Amazon says it'll stream up to 9 hours of audio on a full charge, or last up to three weeks in standby mode. The Tap isn't an always-on by default. To wake it, you need to press the mic on the front. In February 2017, Amazon announced a new firmware update for Tap. With it, you can go to Settings in the Alexa app and enable the new Hands-free option in order to wake Alexa without having to tap the Tap

However, the new hands-free mode will drain the battery quickly, as it requires the mic to stay always-on. Otherwise, Tap can do all the same tricks as Echo (so long as you're connected to Wi-Fi).

Release date: September 2016
Availability: Available in the US (Amazon US order page); available in the UK (Amazon UK order page)
Price: $49 / £49
Dimensions: 38 mm x 84 mm x 84 mm
Weight: 250 grams
Connectivity: Bluetooth and dual-band, dual-antenna Wi-Fi (MIMO)
Power: Plugs into a wall outlet
Audio: Voice-feedback only (Must be connected to external speakers)
Alexa: Yes (Always-on/always-listening/voice-activated)

Echo Dot is 1.6-inch-tall cylinder with one tiny speaker. It's basically just the top section of Amazon Echo - and half the price, but equally as smart. It supports always-on Alexa, connects to the cloud to stream music, controls your smarthome devices, and does all the same stuff as Echo. The original Echo Dot launched in the US in March 2016, but it was refreshed when Amazon announced its UK release.

The main difference between Dot and Echo is that the full-size speaker is gone. The idea is you'll hook Dot up to your own audio setup (via out jack or Bluetooth), so you can use Alexa with your existing speakers. That tiny speaker won't output much audio; it's only for Alexa voice feedback (which, again, requires Wi-Fi).

The new Echo Dot will be available to buy in a six-pack and 12-pack. For those opting for multiple Echo Dots around their home though, Amazon has introduced a feature that will mean only one Echo Dot, and the closest one, will respond to your request.

Release date: April 2016 in US (invite-only)
Availability: Available in the US (Amazon US order page)
Price: $199
Dimensions: N/A
Weight: N/A
Connectivity: Dual-band, dual antenna (MIMO. 2.4 GHz and 5 GHz)
Power: Power adapter (21W) with 7.9 ft. cable
Camera: 5-megapixel sensor
Audio: Built-in microphone array, built-in speaker
Alexa: Yes (Always-on/always-listening/voice-activated)

Details are scarce at the moment, but we know Amazon’s latest Echo device is called the Amazon Echo.

It’s a $199 Wi-Fi camera that offers full Alexa functionality plus hands-free photo and video. Amazon is pitching it as a cloud-connected fashion consultant that allows you to snap pictures of yourself in various outfits. Alexa's software will automatically blur the background in each image to make your outfit pop, and then it uses machine learning guided by "fashion experts" to serve up recommendations about what you should wear.

Amazon called this fashion feature "Style Check," and you can see it in action for yourself in Amazon's announcement video here. Echo Look also works like any other Alexa-enabled device, allowing you to access music, traffic timers, weather, and a vast library of third-party "skills." The device is wall-mountable, too, and includes a a 5-megapixel sensor, built-in microphone array, and built-in speaker.  It also has LED lights (used for the flash).

No other specs have been announced yet. There's also no date set for when the Echo Look will start shipping to customers. Right now, it is available in the US only via an invite-only scheme, with invites going out in "the coming weeks."

Amazon Echo is ideal if you just want to have a stationary speaker that doubles as an always-on personal assistant. It'll provide you with room-filling audio that's sufficient for casual listening but it gets sort of tinny when turned up too much. If you're connected to Wi-Fi, you can ask it all sorts of questions and get it to control your stuff and it is available in the US and the UK.

Amazon Tap is supposed to do all of that, including provide a similar sound experience, but it ditches the cord and uses a charging cradle in order to be portable. As it's not always plugged into power, always-on Alexa isn't available by default. You have to push a mic button to access the service or enable a new hands-free option. Tap is useful if you're going to the beach or are on the go, and it is only available in the US.

As for Dot, just think of it as a little, always-on Alexa hub. It's not a speaker but works with your speakers. It's available in six and 12 packs so you can ensure every room in your home has Alexa listening. And finally, there's Echo Look. Although it has a speaker so you can hear Alexa, we imagine it's not really meant to be a music player. This device is all about snapping photos and serving up style advice.

So, if you're more into music, look at the Echo, Tap, and Dot, but if you're into fashion, the Echo Look might be more up your alley. We'll keep you posted as we learn more about Amazon Echo Look and how it differs from the other devices in terms of specs and functionality.