Vaunt is a synonym to flaunt therefore you are looking for a synonym to disparate which essentially means different.
diverse
When you are presented with
questions such as this, the first thing that you need to do is to determine the
relationship between the first two words.
Thus, because “vaunt” and “flaunt” basically mean the same thing (they
are synonyms), to correctly complete this sentence, you’ll need a synonym of “disparate.” One possible synonym is “diverse.” As such, one possible way of completing this
sentence is as follows: Vaunt is to
flaunt as disparate is to diverse.