MOV is Apple's homebody: gorgeous on a Mac, awkward everywhere else. It was born in 1991, Apple's QuickTime team, and its real weak spot is traveling: Windows, Android and the web would all rather meet an MP4.
WEBM is video the way browsers like it: open, royalty-free and built to stream. A Matroska-based container restricted to VP8/VP9/AV1 video with Vorbis or Opus audio. That makes it the right destination when what you need is embedding on the web without licensing worries.