Often yes it is stated as equal, but his character might prefer Lord instead of Earl so conflict. Some might not care if they get any title, some like him for instance might be really specific on their title.
Referring to a Earl specifically as a Earl is actually more respectful than calling hi Lord XYZ. Not all lord ranks are equal. In terms of hierarchy it went like this:
Margrave > Count/Earl > Viscount > Baron.
Therefore by calling him Earl it is a quiet way of acknowleding his superiority to the Viscounts and Barons of the world.
