Liquid line diameter

I just got my keezer all built and setup. I have two kegs that will be using co2, and one nitrogen setup. I have a question about the nitrogen setup. My kits for my co2 and nitrogen setup came with complete hookups for everything (gas and beer lines) the thing that I am trying to figure out is why my liquid line tubing for my nitrogen system came in a different diameter than my co2 system. So I have two liquid lines at 3/16 for the co2, but the nitrogen came with a liquid line that was 5/16 ID. The liquid line came packaged with the stout tap so I know it is the line intended for use on the liquid side. I’m just wondering why there is a difference.