Play-fighting is part of the natural learning curve for younger Polar Bears.
When cubs play-fight it is typically “cute” & they rough up one another like cats playing.
When larger sub-adults play-fight there is a bit more seriousness in the “roughing-up” department.
Powerful blows which are easily absorbed by the great bears would slay any human.
These two sub-adults were perhaps 7+ feet tall & fairly equal in strength & agility.
The duo was several hundred yards distant but quite visible as they knocked each other about.