I second the answers already given;
As with many other spiritual teachers, I.E.: Jesus, Mohammed. No resemblance was made during their lifetime. According to some sources the first statues where made in the first century and second century in what is now called Afghanistan and Pakistan. So nobody really knows what he looked like.
According to the same site, the sitting version of the statue (the second one you posted), was meant to resemble a bodhisattva called: "Maitreya" and not necessarily Siddhartha Gautama
Lastly I want to add that the Buddha has also been incorporated within Hinduism, as one of the reincarnations of Vishnu. So some of the visual representations of the Buddha or not Buddhist at all.