The designs differ in that the design from a 2011 thread uses a packed tower over the vacuum reservoir. The tower is larger and can support more CFM airflow and as such scrub multiple reactions. Plus the packed tower is not full of solution, the gas flows up through the tower and scrubber water flows down over the packing. Because the wetted surfaces of the tower packing offer more surface area when the gas travels over wetted but not submerged packing, I would say the design from 2011 will be more efficient. The design also pressurizes the reservoir forcing the fume up through the packing after it passes through the reservoir. The 3 cylinder design sucks air through the cylinder by vacuum.
The smaller 3 cylinder scrubber in this thread is for smaller operations, most of which are hobby refiners not needing the scrubbing capacity and more important not having the space the 2011 design takes up in their refining space.
One design uses a venturi to pressurize the tower and force the scrubbed air out through the top and the 3 cylinder design uses a venturi to suck gas through flooded cylinders before it enters the reservoir.
Your choice of scrubbing style will depend on what you are doing and quantity of work you process, you are a new member here so we do not know much about your intentions or existing setup. Welcome to the forum.