This from Darek Kay is a perfectly succinct explanation of the difference between video subtitles, captions, audio descriptions and transcripts:

As I was preparing the requirements for an accessible web video player, there was some confusion around subtitles, closed captions, audio descriptions and transcripts. In this post, I use interactive examples to show the difference. I also provide related success criteria from the Web Content Accessibility Guidelines (WCAG).

I'm sure there will have been times where I have previously talked about subtitles when what I really meant was closed captions. Maybe for you too?

If you create videos of any kind, this is the sort of stuff you should know. And of course, video-making tools are now so much better at helping you create and add subtitles, captions and transcripts. There isn't much of an excuse to not make your video content accessible.

For example, I use the excellent Descript to make podcasts. Add an audio or video file to your project and the app will auto-generate a transcript for you. The transcript is never perfect, but it gives you a fantastic start by doing the bulk of the work for you. A few tweaks and it's ready to go.