I'm working on an Alexa skill (for Echo), and i've looked into Alexa skill kit from the very start.
Now, i'm confused about Alexa Voice Service. i've read documentation on Amazon, but cannot understand it in a better way.
Please guide about What's AVS? And how is it related to Alexa skills?
The Alexa Skill Kit is for creating skills that specifically run on the Amazon Echo or any other device that contains Alexa.
The Alexa Voice Service allows you to add Alexa's voice control to any product that has a microphone and speaker.
To Read more about Alexa Voice Service check out this link: https://developer.amazon.com/alexa-voice-service#How%20AVS%20Works
Alexa Skills Kit is for "making Alexa smarter" through developing custom skills.
Here's the SDK in Node.js that Amazon released on GitHub.
The prerequisite for these skills is that the user is already using an Alexa-enabled device, like the Echo or Echo Dot.
Alexa Voice Service SDK allows for device users to enable Alexa on any device with a microphone and speaker.
Here's the SDK in C++ that Amazon released on GitHub.
This means Alexa can end up in anything from a car to a smart fridge, if this SDK is used, which is super exciting!
Alexa Skill Kit (ASK) is for building skills that users will access via the Echo or other Alexa enabled devices (or apps).
The Alexa Voice Service (AVS) is for building those 'other Alexa enabled devices (or apps)'.
AVS (Alexa Voice Service) is for existing or new physical devices. If you add the AVS libraries, you can essentially turn that physical device into an Alexa-enabled device.
ASK (Alexa Skill Kit) on the other hand, is what helps you build "skills" for Alexa. BTW, you can still add skills for any device that you connect via AVS.
Alexa Voice Service
There are many ways to interact with Alexa -- with the Tap, Echo, Echo Dot, Echo Look, Echo Show, Dash Wand and the Amazon Fire TV. However, Amazon extended Alexa to third-party device makers through the Alexa Voice Service (AVS).
The AVS Device SDK provides C++-based libraries that enable any commercial device to process audio inputs and triggers, establish persistent connections with AVS, and handle all Alexa interactions.
Alexa Skills
The Skill Kit allows you to customize your Alexa conversation by building your custom skill. Skills are like third-party applications for Alexa speakers. There are more than 20,000 custom skills. For example you may say: "Alexa, open Jeopardy". You need to enable it to be able to use it.
I think of AVS as an API to integrate Alexa into any 3rd party hardware that has the capabilities of alexa (mic and speaker)
How AVS relates to ASK: -AVS just has the same abilities of ASK, but isn't really used for anything specially amazon. I think AVS is more so again for 3rd party hardware so in building alexa skills there is no need to focus on it.
来源：https://stackoverflow.com/questions/40994082/alexa-skill-kit-vs-alexa-voice-service