Cantonese and Taiwanese are part of Chinese dialects,people from Guangdong province and Hong Kong speak Cantonese,people from Taiwan province speak Taiwanese,but I think people from these regions could also speak Chinese now.There are also many other dialects in China,such as Goetian (a dialect that is spoken in Suzhou,east of China),Shanghai dialect,Beijing dialect.Beijing dialect is similar with Chinese.In China,many northern dialects are similar with Chinese,but southern dialects are not,people from south China could undertand northern dialects,but north Chinese may not understand south dialects well.Mandarin is the official name of Chinese,I think there is no exact difference between Mandarin and Chinese.There is also an opinion that Mandarin is the old name for Chinese,I think Chinese may more modern than Mandarin.

All varieties of Chinese are tonal. This means that each syllable can have a number of different meanings depending on the intonation with which it is pronounced. For example Mandarin has 4 tones, Cantonese has between 6 and 9 (it depends who you ask) and Taiwanese has 7 tones. The major varieties of Chinese are mutually unintelligible, but most people in China and Taiwan who don't speak Mandarin as their first language, can speak or at least understand it a bit. However in Hong Kong and Macau few people speak Mandarin, so they tend to use English to communicate with people from other parts of China or Taiwan. Each of the major varieties of Chinese has numerous dialects. For example, Mandarin can be divided into northern, southern and south-western dialects, which are more or less mutually intelligible.

Mandarin and Cantonese are two two SPOKEN styles/dialects of Chinese language. As an official spoken “dialect”, Mandarin is widely used in Mainland China, Taiwan area and Singapore. Cantonese is specifically for Hong Kong and some overseas Chinese communities. If your goal is to be widely understood, you should learn Mandarin because Mandarin can be understood even in Hong Kong, Macau and Canton (the main regions who still speak Cantonese), and more and more Cantonese speakers are learning Mandarin nowadays. If you really want to be able to connect with people from Hong Kong, Macau, and Canton, you can still consider learning Cantonese. But you should still know that Cantonese is often seen as more difficult. Its use of “tones” can be even more challenging to western speakers than Mandarin. I have a small article that might be of your interest: <a href="http://www.actranslation.com/chinese/chinese-mandarin-cantonese.htm"> Mandarin vs. Cantonese</a> It’s easier to find people to teach you Mandarin, including some of your Chinese friends who have learned “proper Mandarin”, and who may be able to teach you the language step-by-step; More Mandarin learning materials are available from all sorts of sources and at a variety of levels; With the current economic growth of China, it’s likely that Mandarin will be a key language of the future. Alternatively: Knowing how to speak Mandarin is not such a unique skill as compared to in the past, as more and more foreigners live in China and have learned the language; For someone whose English is not their native tongue, it might be better to, firstly, improve their English as more and more Chinese students and business people across the country are learning English.

you could call them dialects but it is not quite exact. all are different ways of speaking chinese. mandarin is the international name to denote pu tong hua: common language, mainly based in peking dialect. there are 5 major tipes of chinese, and they are not totally intelligible among them. look info in any book on library for more details.

Cantonese and Taiwanese is dialect,mandarin is the ancient official language.Chinese is the modern official language.I merely know these.