Disparity in death numbers are very common in chaotic scenarios: wars, epidemics, famines...
Even now, we don't know exactly how many people died in WW2.
Even worse, in any catastrophe, authorities usually report the number of confirmed deaths, while other sources give estimates of total deaths. In Gaza, those two numbers are very unlinkely to match now. With so many displaced people, and the fact that saving the living must always take priority over counting the dead, I am not surprised at all by the 10x disparity.