Originally Posted by Zandel

Rewards for Raid bosses (ALL RAID BOSSES) is based on BOSS LEVEL and NOTHING else.

It also depend on the type.

Originally Posted by Zandel

You will ALWAYS get the same rewards for 2 bosses of the same type and same level.

I can also confirm that.

For the event boss, the rewards are as follow:
Dummer Bee => (Lv + 9) Dahma Nactar Spheres
Nemura Dummer Bee => (Lv + 19) Dahma Nactar Spheres

The Seedy Seed and the Queen Wasp gives the same amount of equipment seed for the same level.
(but it's not linear)
The Scoll Scoville gives much more equipment seed for the same level.