Its an apples to oranges thing. Comparing two objects that are not the same object, and asking why one looks better than the other.
Its an argument that doesn't work, because the objects cannot be compared because they are two different objects.
Had the OP said "Why does Ifrit egi look cool, but garuda egi look like cat vomit" it would have been a good comparison because they're both egis.
But comparing mounts to egis doesn't make sense because they're not the same.
https://en.wikipedia.org/wiki/Apples_and_oranges