the difference between partly "and" partially

zyc50

http://www.bartleby.com/68/36/4436.html
These adverbs are largely interchangeable, although some commentators insist
that partially means only ¨to a limited degree〃 (My liver and bacon were
only partially cooked; they were practically raw), and partly means only
¨in part〃 (My lunch was only partly cooked; the salad and vegetable were
meant to be served cold). But in fact these distinctions are doubtful: The
stream was partly polluted and The stream was partially polluted mean
precisely the same thing to most Americans: any distinction you establish
will probably come from context, not from the choice of adverb.