What GP is saying is that while Java is object-centric, R (and CLOS etc) is method-centric: you don't have classes with multiple methods, you have generic functions with multiple methods (each of which implements that function for particular argument types): http://adv-r.had.co.nz/OO-essentials.html#s3

This is not about functional programming at all; the distinction here is completely orthogonal to that.