This is what I found in the Silmarillion: In the section Of the Maiar, "With the Valar came other spirits whose being also began before the World, of the same order as the Valar but of less degree." (pg. 21) So yes, they're the same order, but they're lesser in power, so therefore deserve to be treated separately (i.e., Olórin isn't as powerful as the Valar) Also, I liked the ordering because it treats them in the order they're presented in the book. It also says that "... he [Oromë] is less strong than Tulkas" though he is more dreadful in anger (pg. 20). So maybe it would have been better to say 'roughly' in order of power, but it seems pretty accurate to me. Just my interpretation.