 The popular fiestas of Ibiza are much less pretentious than the equivalent (and more famous) ferias of mainland Spain.
Fiestas happen more often in Ibiza than ferias do in mainland Spain.
mnli hypothesis: Fiestas happen more often in Ibiza than ferias do in mainland Spain. premise:  The popular fiestas of Ibiza are much less pretentious than the equivalent (and more famous) ferias of mainland Spain.