Both of these are metrics used on a video for a page. How you fetch these metrics is slightly different.
So both of these are used to show "The number of times your videos played for at least 3 seconds...". Additionally, these both are returning the same value for all my videos.
What I am interested in knowing is what makes these different? Which one should I use?
The same video could be used in multiple posts - a video uploaded once, can be used as source for new video posts, instead of uploading a completely new one.
So post_video_views gives you the views of that video as part of a specific post, and total_video_views the overall views for the video.
Additionally, these both are returning the same value for all my videos.
Yes, if you didn’t use any of those videos multiple times, then both metrics will be the same.