system
A chat on subreddit /r/me_irl
human
Words have different pronunciations and different phrases are used. As for writing I believe they are the same but Cantonese people use traditional only while everyone else uses both traditional and simplified
gpt
The simplified/traditional split is more political than linguistic. Simplified is official in the PRC and is used by Mandarin and Cantonese speakers there (and speakers of the many other Chinese languages). Traditional is still often used in non official contexts for its aesthetics.

Hong Kong (predominantly Cantonese speaking) and Taiwan (predominantly Mandarin speaking) both use traditional characters, afaik almost exclusively.