Snooker CB is smaller than the object balls (OB).
Standard American tournament pocket billiard balls - CB is same diameter as OBs = 2.25".
A bar box CB is oversized relative to OBs to allow for return.
The balls in the picture are racked for either 14.1 or one-pocket.
For an 8 ball rack, the 1 ball must be in front.
For rotation games, the 15 ball is the head ball, the 2 and 3 balls are racked behind the 15. The 1 ball is in the middle of the rack with the 13 & 14 balls behind the 1 ball with the rest of the balls placed in any order.
Assuming a game is about to be played, somebody racked those balls for a high-skill game. I'd like to think for one-pocket.