Philos Hippos, please do another test: enter 1 word in a cell, 2 words in another cell and 3 words in a third cell. Format these 3 cells, so that they will have Distributed vertical alignment. Length of the words and column widths should be such that there will be one word per line. Now make a copy of these cells and format them, so that they will have Justify vertical alignment.

You will see that the difference is apparent only in the cells with a single word: Justify aligns it at the top whereas Distributed centers it vertically.