Note that "whatever" in Minnesotan doesn't have the same connotations that it does in other places. "Whatever" in Minnesota is accompanied by a long sigh. When we say "whatever" we mean it - we're resigning ourselves to a fate we have no control over that usually doesn't please us. Minnesotans would not be pleased by the prospect of eating frozen yogurt. "I'm afraid you have cancer and have but six months to live." Whatever. "I'm going to have to rebuild your engine - it'll cost a pretty penny." Whatever.
When a Minnesotan says, "That's different" he means it. It's not merely a way to make a non-committal reply to something utterly outlandish (to a Minnesotan, organic granola bars are utterly outlandish) but, rather, a simple sentiment. "We're going to Bombay on our honeymoon." That's different. "I've dyed my hair red." That's different. "We prefer soy milk." That's different.
Another closely related term to "that's different" is "that's interesting". A Minnesotan would never say, "That's interesting" because, as an interested party, you would be expected to follow up with questions of your own. That just will not do. Just about the only question that comes up in a typical conversation in Minnesota is, "You don't say?" "You don't say?" is closer to "That's different" than "That's interesting" than you might think.