u/dty6

As for that fist bump between Biden and the Crown Prince:

"The fist bump is one of the few gestures that is equal," he tells Goats and Sodas. "You could do it with President Obama, and you'd both be equals at that time."

That's because the knuckles are meeting at the same level — neither bumper has the upper hand, so to speak.

By contrast, a handshake can turn into a contest: Who's got the stronger grip?

https://www.npr.org/sections/goatsandsoda/2014/07/19/331809186/in-the-world-of-global-gestures-the-fist-bump-stands-alone

We've all seen Trump dominate another person with his handshake. You are never in doubt who's in charge when Trump shakes hands.