Oh that definitely explains the violin viola thing then. They're so close that to outsiders the might not even know which is which (especially since there are 1/2 and 3/4 scale versions of each). To outsiders the animosity there is puzzling, but their very similarity explains it.
Of course, there are also all the jokes about the viola going out of tune all the time…The other subtle difference is that they require different fingering technique because the reach is too much to use violin fingering on a viola.
But then I look at Celia Hatton and forget about all that.