You are right, Iowa and Utah are similar in terms of research strength. However, overall Iowa promises notably better career prospects, and presumably this has played a major role in the voting process here. Remember, the former has had a long, distinguished tradition of success while the latter's ascension has been more recent.
I compared Iowa and Utah in terms of placements; my earlier conclusion was premature, as they have performed similarly, esp. in the recent several years. This attests to the rapid rise of Utah.
Faculty research at Utah is indeed more active and prolific.