RG-6 is pretty much the standard now days. It is typically used for sat/cable. RG-59 used to be used for cable connections, it's possible that Keystone still uses it as a cost saving measure. RG-6 has a better shielding as well as a better center conductor. It provides a cleaner signal and transfer data better, especially the digital signals used these days. Regardless of what is internal to your RV, connecting to the RV with RG-6 will work for both applications.
2013 Alpine 3500RE
2019 Silverado 2500HD Duramax
U.S. Air Force Retired (25 yrs)