Side note: the written language that Beijing requires all school children to learn is usually called "Standard Written Chinese" even though it's based on the grammar of Mandarin. Depending on the differences in grammar between the local dialect and Mandarin, it's more or less difficult to learn the standard written grammar. We usually don't say "written Mandarin", but less formal writing using the grammar of one of the other dialects would usually be called "Written Cantonese". etc.
My manager speaks a dialect that's pronounced differently, but has a grammar close to Mandarin. The majority of people here in Hong Kong speak Cantonese, which is grammatically more different and uses a lot more slang and references to popular culture. I'm told that growing up here, leaving at age 15, and coming back at 25 makes it very difficult to follow daily conversations and read certain types of publications for the first few months because of the amount of slang used and how rapidly Cantonese changes.
My manager speaks a dialect that's pronounced differently, but has a grammar close to Mandarin. The majority of people here in Hong Kong speak Cantonese, which is grammatically more different and uses a lot more slang and references to popular culture. I'm told that growing up here, leaving at age 15, and coming back at 25 makes it very difficult to follow daily conversations and read certain types of publications for the first few months because of the amount of slang used and how rapidly Cantonese changes.