I just had a look at both of them, and I think they're a little different.
Apart from the disparities in size (the medium realistic bent is shorter and girthier than the Tex), it seems as though the head of the MRB is more pronounced than the Tex's. But then again, that could be because of the size difference, or the angle at which the pictures of them are taken.
To be sure, you could go over to the Vixen forum thread (link
) and ask them