Video transcription transforms the audio in your video into text by employing either human transcriptionists, software that recognizes speech, or a combination of the two. If there is no video transcription, your videos will only use audiovisual content to convey information. The main reasons to add video transcript are
1- It improves your search engine optimization
2- it create a better user experience.
3- It increase the accessibility to users who are deaf and hard of listening.
The difference:
1- Proprietary work.
2- Priority base work.
3- Guarantees on quality, deadlines and support.