Heres why. Both use fire magic and wield tridents both are kings one being the demon king and one being the king of monsters both live in places very different from the surface or overworld both have a similar build with one being a pig like humanoid and one being more similar to a goat thats about where the similarities end they are very different characters with ganon being pure evil and asgore was pissed about both of his kids dying and for his kingdom they use their weapons differently ganon spins his to create fire bats and throws it while asgore swings it and uses it to destroy the mercy button