Ask kbin tech: Whats the difference between an HEIF/HEIC animation, versus a video-track-only HEVC video? Same question for AVIF vs AV1?

I know that HEVC isn't a file format, but I can't comprehend all this. Is it the buffering? Size? Video player's behaviour?
Can I rename the HEVC.mkv to HEVC.heif and let the browser play it like a GIF? And the same for AVIF vs AV1? Did not have time to read all the docs.