Orb uses the same ball-shaped plastic tip idea as Ball but at a noticeably smaller diameter, and that single change alters its behaviour completely. The reduced contact patch means less friction and much less mobility: an Orb combo circles briefly after launch and then settles almost stationary in the centre, closer to Needle than to Ball. Because it stays put, you can launch it as hard as you like without worrying about it wandering onto the X-Line.
The trade is that a stationary top is an easy target for an attacker who knows where it will be, and the narrow tip gives it worse knock-out resistance and a harder time righting itself once shoved off axis. It tips over earlier in a long grind than Ball does.
Orb’s real home is stationary-defence work under blades with decent recoil control. It is a legitimate second choice, but most players reach for Ball first and only bring Orb out when the matchup rewards sitting still.