Holden Karnofsky thinks superintelligences with utility functions are made out of programs that list options by rank without making any sort of value judgement (basically answer a question), and then pick the one with the most utility.

Eliezer Yudkowsky thinks that a superintelligence that would answer a question would have to have a question-answering utility function making it decide to answer the question, or to pick paths that would lead to getting the answer to the question and answer it.

Says Allison: All digital logic is made of NOR gates!

Says Bruce: Nonsense, it's all made of NAND gates!

Allison: Look, A NAND B is really just ((A NOR A) NOR (B NOR B)) NOR ((A NOR A) NOR (B NOR B))

Bruce: Look, A NOR B is really just ((A NAND A) NAND (B NAND B)) NAND ((A NAND A) NAND (B NAND B))

(Edited because my lines of text got run together)

Edited again: I'm not trying to say either is a workable path to AI-completeness, just that showing that you can make some category of device X classified by ultimate function, and ignoring internal workings, out of devices of category Y, doesn't mean that Xs have to be made out of Ys