HP difference is 97, assuming the paladin will make use of the 10STA on the FD, which is very likely. But the AC difference is 30 in favor of the ND. With
Loraen's rough guide that 1AC=3-5HP, the extra 30AC of ND puts it roughly equal to FD at 90-150HP vs melee damage. However, if the paladin is already at the AC softcap through other means or AC is not as Loraen describes, then the FD again comes out on top.
The FD is a better weapon than ND, but not by as much as people think. And as already mentioned the Nature's Defender is easier to obtain than the Fiery Defender.