In talking with our team here these model numbers are for the same functioning valve. The model you are requesting (4110A-6"-3.6K-HL-NC-D-SR15-3.6K , 2- Way Valve) is an older cast version of the valve. This is something we no longer offer. We DO NOT offer this version of the valve anymore.
The new model (4110A-6"-3K-HL-NC-D-SR15-24/6 Spl., 2-Way Valve) functions the same and has the same abilities but is a forging. This is the newest version of the valve.
The last number does have to do with the operating pressure. Please let us know what the operating pressure will be on the system.