Videos - do we need both captions and transcripts?

Hello All,

I have a super elementary question, what is the difference between prerecorded and synchronized video?  From what I can gather, it seems there is a level of interaction with synchronized video, like online tutorials or eLearning. Am I close?

Transcript are for prerecorded (according to this Section 508 checklist item 2.2<https://www.hhs.gov/web/section-508/making-files-accessible/checklist/html/index.html?language=es>) and captions are for synchronized (checklist item 2.3).

If this is irrelevant and you advise using captions for all video content (except for a silent movie, of course) or if we need both captions and transcripts?

Thank you again for all your advice.

Thanks,
NJ