About the Web Speech API

Web Speech API is an API specification published by SpeechAPI Community Group.

This specification defines two APIs: SpeechRecognition for voice recognition and SpeechSynthesis for voice synthesis.Of these, the former SpeechRecognition is offered as a webkitSpeechRecognition in Chrome.This webkitSpeechRecognition is a class that implements the SpeechRecognition interface mentioned above.

By the way, SpeechSynthesis doesn't have a prefix in Chrome, but I don't think I'll be aware of the name directly because I get it from window.speechSynthesis.

Note Web Speech API - Web API Interface|MDN

Google Speech API, on the other hand, is an API for Chromium browsers that is used via HTTP, such as Maps API and Drive API.The usage will appear when you google it, but as mentioned above, it is not a general API.Token will only be issued to participants in the Chromium developer ML and the number of calls is limited.