Closed Captions display audio as text on a screen for a pre-recorded event/video.  With closed captioning the user has the ability to turn the captioning on or off.  

Live Captions or subtitles are when text is displayed on the screen in real time as a person is speaking. 

Described and Captioned Media provides captions as well as text description of other sound elements in a video.

Live Captioning and Closed Captioning Tools

3rd party PAID Closed Captioning Services
Best Closed Captioning Services