For Mandarin speakers who are trying to learn Cantonese vocabulary and/or make an effort to read written Chinese in Cantonese; you will quickly discover that there is nearly always 2 forms for each word: The written version and the spoken version. It amazes me how Cantonese learners/Hong Kong students learn to write/read Chinese (based on Mandarin) and speak Cantonese. The words and grammar can be so different that you wonder how people manage to achieve any written fluency.

An example I’ll give is: What do you want to eat?

Spoken:
你想食乜嘢呀 ?
nei5 soeng2 sik6 mat1 je5 aa3?

WRITTEN:
你想吃什麼東西 ?
nei5 soeng2 hek3 sam6 mo1 dung1 sai1?

Especially listening to Cantonese music (eg. Canto Pop), the lyrics are more often than not exclusive to Written Chinese in Cantonese pronunciation. In fact, all newspapers and books are written in written Chinese (based on Mandarin), so to be read by all speakers of other dialects. In some cases; writing in Oral Cantonese is discouraged, though can be seen on Internet chats, forums and entertainment magazines.