There seems to be various romanisation methods of the Chinese Language. Pinyin is the official one used right now in the teaching of the language in many countries including mine in Singapore. In Taiwan, Bopomofo instead of Pinyin is most commonly used, but I think they are also adopting Pinyin in their education now.
The Pinyin we used here is called HanYu PinYin. HanYu is standard Mandarin that the whole of China used. Hanyu is called PuTongHua (common speech) in China or GuoYu (national language) in Taiwan. In Singapore it's called HuaYu (chinese language).
Cantonese is a dialect and is spoken differently than Mandarin. Personally to me, Cantonese is like another language and I don't understand 90% of it. Cantonese is a popular dialect as it is used in Hong Kong, Macau and Guangdong, the most populous province of China.
And yes, there is Cantonese PinYin, which is different from HanYu PinYin. Besides Cantonese PinYin, there's also Jyutping.
I'm already confused now.