Ursula's Discussion Question from Chapters 17-21

Melville places special emphasis on names in Moby Dick. By choosing two very well known biblical names with clear biblical stories he gives them an edge of pretense. That being said, is there a clear correlation between the two main names: Ishmael and Ahab. If so, what is it? Does Melville suggest similarity through the two's "misfit" natures? Or difference?