"Google show camera on cast" vs "camera.Play_stream"

Is there a difference in what happens when you say “Google show camera on cast-device” and what happens if you use the HA play_stream to a media player that is a cast device?

Neither seems to work reliably for me, though the latter seems more reliable than the former, and am trying to understand what happens so I know if that difference is significant or random noise.

On a related note, is there a more technical description (other than the code I guess) that would help one debug issues? About half the time I just get a time line and no image. Just do it again it may work (or may not), no rhyme or reason that I can see.

Thanks,

Linwood

PS. Note using the cloud google integration not manual if it matters, on 0.92.2