Massive difference in taste between UHT and pasteurised but you must understand there's different use for either. I did a course on espresso coffee and clearly remember the teacher telling us that for the best cappuccino you should use full fat UHT as opposed to pasteurised milk. You'll also notice that many coffee chains use UHT. On the other hand eating cereal with UHT has a funny taste. Either way the benefit of UHT is that it can be stored without reliable refrigeration, especially useful in developing countries with a sparse or unreliable power grid.