I say that physicists are smarter than mathematicians. You say?

As a mathematician I find this question vaguely formulated. Which criteria should one use to decide whether a group of people is more intelligent than another group of people, the average IQ of the group, the highest IQ in a group? As far as the two groups mentioned in the question there are “embarrassing” situations such as, Edward Witten, a physicist being awarded the Fields prize for mathematics and Sir Roger Penrose, a mathematician being awarded the Nobel Prize for physics.