Mandarin and Cantonese are not two separate languages. They're both dialects of Chinese. In fact, there are many (I'm not sure of the exact number) Chinese dialects, most of which sound so different from each other that you'd not know they were from the same language. It's not at all like a Southern accent is different from a North-Eastern accent in the United States, where "twang" aside, it pretty much sounds the same (no southen accent jokes, please!).
"Simplified characters" notwithstanding, written Chinese is the same for all Chinese people, no matter where they live, so that even if you spoke an entirely different dialect than the region you're visiting, if you can read Chinese characters, you can essentially communicate with any other literate Chinese person by writing.
And what's in a word? Would a word by any other name smell as...confusing??
Cartoon by the brilliant Sidney Harris in the book You Want Proof? I'll Give You Proof!"He is happiest, be he king or peasant, who finds peace in his home." ~ Johann von Goethe
