There are two systems of Chinese characters, which are used when we want to write something down:traditional and simplified. These are the real Chinese "words". In mainland, simplified Chinese characters are polular, while in Taiwan and Hongkong what you see are traditional. Pinyin is another system introduced in 1958 that helps the Chinese beginners(both foreigners and the Chinese kids) to pronounce the characters.(no matter it is traditional or simplified) Mandarin Chinese is the speech of officials and what most of the Chinese speak or can understand, if you know there are so many dialects in China... So i think it is better for you to learn Mandarin Chinese(not a dialect ).And at the beginning Pinyin will surely help you with the pronunciation. If you are not just satisfied with listening and speaking , you also want to write in Chinese, the learning of the Characters is also full of fun.