There are formal and informal Cantonese. Usually we have to use formal Cantonese in reading and writing, we use informal Cantonese only in dialogue, e.g., the formal Cantonese for “he” is “taa1” and “keoi5” in informal. Look at the table of pronoun below:

We can see that not all the Cantonese words have informal form (bold italics), sometimes, we use formal Cantonese in both speaking and writing.