What is the difference between Cantonese and Mandarin and Chinese?

To understand it the easy way, there is one written language (*Chinese) shared by many spoken languages (Cantonese, Mandarin, Shanghainese, etc) in China.

Some more details:

(1) Mandarin is the official spoken language in China, spoken by most Chinese people (as first or second language - some Chinese have their own regional languages)

(2) Chinese government called Cantonese a dialect; while in fact it's a language

(3) Cantonese is the official spoken language in Hong Kong and Macau and the sixth biggest language (by speakers' population) in the world (second biggest in China)

(4) Cantonese is more difficult to learn than Mandarin (mostly because it has 9 tones, Mandarin "only" has 4)

(5) Hong Kong people take so much pride in Cantonese - we think Mandarin is "meh" 

Flash cards for learning Cantonese. Not my creation.

*There are actually two versions of Chinese writings: Traditional Chinese and Simplified Chinese. Simplified Chinese sucks.