OK all you librarians, dictionary thumpers and English majors out there: What's it called when you have one of those reversal of word/idea sort of sayings, like "Not blind resistance to progress, but resistance to blind progress" or, from a pop song, "If you can't be with the one you love, love the one you're with". There must be a term for this type of statement ?

Also, not quite the same, but one I hear frequently is the 80/20 rule - "80 percent of the wealth is owned by 20 percent of the population" etc. What's that type of saying called ???