“fustian” and “pretentious speech” and “pompous speech” can be similar/related but they don’t map 1:1 to each-other. Fustian is a type of cloth which was used

“fustian” and “pretentious speech” and “pompous speech” can be similar/related but they don’t map 1:1 to each-other. Fustian is a type of cloth which was used as padding. If I say I just listened to 10 minutes of fustian from a politician that means they were filling time far beyond the direct content. I would characterize many business books as fustian. (Or at least, this has always been my understanding of the word.) If I say the speech was pretentious that means it was artificially pretending to be something it wasn’t, e.g. as if it were written by someone who looked up every word they wanted to use in the thesaurus and then chose the most obscure quasi-synonym without knowing its meaning and without bothering to check that the new word actually meant what they wanted to say. (There might be other types of pretension. For instance, someone might say that a highly-educated upper-class politician’s speech is pretentious when he talks like a manual laborer, or that a political scientist’s writing is pretentious when it reads like a physics paper.) If I say the speech was pompous, that means it was affectedly grand; imagine someone giving a speech at a city council meeting about whether to add some bike lanes to a local street but sounding like a king’s eulogy. “Fluff”, “stuffing”, “padding”, “bombast”, “hot air”, etc. are ways of expressing more or less the same metaphor as “fustian”.