In ValueList() you give a list explicitly separated by comma, like ValueList(V1, V2, .....), while in ValueLoop() you can give starting and ending values and third parameter to tell the step. That means, if you write valueLoop(10, 20, 2), you get values string from 10 and ending at 20 with gap of 2, so the output : 10,12,14,16,18,20. In short, In ValueLoop() you have to setup a rule to generate values, whereas in ValueList() you have to mention the values itself.
