The phonology differs. Vocabulary differs. Grammar differs. Speaking Cantonese and Mandarin natively, I have no idea what Hokkien or Sichuan people say, whether or not you write it down.
This is especially apparent when speaking to less educated people with less exposure to the standardised, official Chinese language, which is what people do actually write down when intending for a broader audience, of course. Diglossia is real.
Yep. Anybody who’s ever read written Cantonese or Shanghainese would realise they are often unintelligible unless you speak those languages and understand how they’re written. eg 「佢冇做乜嘢」
And yet the incorrect parent comment has been voted to the top of the thread by those who think it’s helped them.
This is especially apparent when speaking to less educated people with less exposure to the standardised, official Chinese language, which is what people do actually write down when intending for a broader audience, of course. Diglossia is real.