I think that means something like all the individual values in the @ar1 list of values are less than at least one of the individual values in @ar2.

Yes exactly. To take the code snippet a cousin-reply mentioned one step further, swaping @a and @b:

    > my @a = <1 2 3 4>;
    [1 2 3 4]
    > my @b = <2 3>;
    [2 3]
    > say so all(@a) < any(@b);
    False
    > say so all(@b) < any(@a);
    True