Chinese: Natives of China,or People with Chinese heritage living overseas & language
Cantonese: dialect of Chinese language
Mandarin: dialect of Chinese language
Cantonese and Mandarin = different dialects of the Chinese language. Most schools will teach Mandarin, so in those situations, Chinese = Mandarin, but not necessarily. xal is wrong: Chinese = Mandarin only in a restricted sense. There's 20+ dialects in Chinese. With plenty more sub dialects and sub-sub dialects. The common or official language used in China is called Zhongwen or zhong guo hua or putonghua, not Mandarin. Mandarin is a word that came from Mandarim from Portuguese to describe the officials of ancient China.
The symbols are more complex (sophisticated)
Read what you wrote, and look it up online first, before saying something totally unacceptable.
mandarin is spoken by Chinese usually from Hong Kong. Really? People from HK speak Cantonese!
there's no such thing as Chinese-Sinitic. The word Sinitic is from Latin. The language group is called "Sino-Tibetan", not Chinese-Sinitic!
Please do some research online before posting comments that's considered incorrect or misguiding!