If you see in a file name, it is almost always the best version to download , as it solves a known problem found in the "Internal" or original release.

The site or group that encoded/uploaded the file.

A "proper" release is issued when the initial upload contains one of the following issues:

Missing lines, poor timing, or major translation mistakes.

Indicates the source is a Blu-ray Disc (BD) rather than a TV broadcast, typically offering higher quality and uncensored visuals. MP4: The video file container. ✅ Summary

Artifacting, dropped frames, or encoding errors.

The sound doesn't match the characters' lip movements.