Voice assistants and voice user interfaces (VUIs) are used interchangeably under the banner of ‘voice’. But what’s the difference between the two?

Voice assistants have a voice interface, but voice interfaces aren’t always an interface to a voice assistant. Click To Tweet

What is a voice assistant?

Google defines voice assistance as:

“Engaging with intelligent technology using voice as the method of input (e.g. a digital assistant like Google Assistant.”

Google's definition of voice search vs voice assistance
Image used with permission from @andy_head, CEO, Adido

WhatIs/Tech Target defines a voice assistant as:

“a digital assistant that uses voice recognition, natural language processing and speech synthesis to provide aid to users through phones and voice recognition applications”

The key word there is ‘aid’. A voice assistant aids and assists users in whatever it is they need assistance with, using speech as the primary method of receiving requests and responding.

That could be assisting you in accessing your calendar schedule, assisting you in finding a podcast, helping you get the news and even navigating through the apps on your phone, as we witnessed with the Google Assistant announcements at Google I/O ’19.

A key component of a voice assistant is the ability for it to access lots of different pieces of information from lots of different sources and funnel it all through one place.

For example, with Alexa, you can access you calendar, send SMS messages, book train tickets, order pizza and check your bank balance. Lots of information from lots of sources, all pulled through one place and accessed via voice.

Google Assistant, Alexa, Siri, Houndify, Mycroft, these are all examples of voice assistants.

What is a voice user interface?

Amazon defines a voice user interface (VUI) as something that:

“… allows people to use voice input to control computers and devices.”

A VUI, then, is an access point, in the same way a screen is an access point to a graphical user interface (GUI).

A voice interface is a front-end. A way of interacting with software with your voice, instead of tapping or typing.

For example, Spotify has just launched voice enabled ads in the US:


At the end of the ad, listeners can say ‘play now’ to play the advertised playlist. Using your voice to interact with the software instead of tapping. It’s not an ‘assistant’, it’s an ‘interface’.

Voice assistants have a voice interface, but voice interfaces aren’t always an interface to a voice assistant.

Hopefully that’ll help clear things up next time you read or talk about voice.

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