The 1975 World Series is infamous for an umpire term called “tangle untangle” wherein the batter came out of the box and collided with the catcher. This is purely a judgement call where it must be determined the severity of the collision and who is in most violation. If the catcher shoves the batter to the ground, it is obstruction. If the batter shoves the catcher to the ground, it is interference. If they just bump each other both doing what they are supposed to be doing and no one gains an advantage, you may see the umpire give the “safe” signal indicating he has determined this to be “tangle untangle” and everyone should play on.