Do Streams / Videos consume less data volume over the phone?

I currently have no Wi-Fi and I would be interested in whether it draws less data when I watch a stream over the phone, than a NEN hotspot with the laptop, or whether that makes no difference.

That depends on what quality you watch the video with. Whether you are watching a video in 1080p on your mobile phone or laptop makes no difference.

With the mobile phone you can easily downgrade the quality and it looks thanks to the little Bildschim at least better than on the laptop.