This is maybe a bad example, but it's what comes to mind: think of the bitterness of a Sierra Nevada Pale Ale (which, AFAICT is heavily Burtonized) versus the bitterness of a Pilsner Urquell. They are probably just about the same IBUs, but the SNPA has a "sharpness" that PU does not. True, this is probably as much to do with the hop varieties, fermentation, and grainbill differences, but... y'know.
Too much Burton salts makes you all parched the morning after a bender.

