Athletics: The javelin men's WR is 10 meters longer than the hammer WR. The hammer women's WR is 10 meters longer than the javelin. Any explanation?

In both cases, the men's throw uses a heavier object than the women's, but the ratio is very different:

Men's hammer is 7.62 kilograms, while the women's is 4 kg, a ratio of 1.9 to 1.
Men's javelin is 800 grams while the women's is 600, a ratio of 1.33 to 1.

(Edit:) Or, if we compare the objects by gender, the men's hammer is 9.5 times the weight of their javelin, while the women's is only 6.67 times as heavy.

Thus, the women's weight lineup favors the hammer while the men's favors the javelin.

https://en.wikipedia.org/wiki/Javelin_throw
https://en.wikipedia.org/wiki/Hammer_throw