China is a huge country, and it is hard to believe the majority of its population can speak the same language. As a matter of fact, the only country with a similar size in population and territory – India – is not as linguistically unified as China.
China is not different from other countries though – there are dialects and local languages, and of course the standard mandarin is being promoted in schools and public life, but it is not the only language people use. Just like there are different kinds of english according to the area (e.g. British English, American English, Canadian English, Indian English…), there are also different types of Chinese. But, at the same time, it’s not exactly the same thing.
Written Chinese, thanks to the usage of characters, has been for long a unified language, which means anybody who reads any kind of Chinese language or dialect will automatically be able to read any other kind: this means that the problem is only present at a oral level.
Indeed, although the meaning of the characters is standardized, that is not the same for the pronunciation, which can vary according to the dialect or language you will use.
While Putonghua (or standard language) is very widely understood, the regional accent of the speaker can sometimes complicate a oral conversation, especially for less linguistically educated people. Since China has huge internal migration, the usage of Putonghua is more and more needed by both migrants and local residents, who will both need to set aside their own dialects and languages to understand each other.
If you need an interpreter, you will surely want to get somebody with a very standard Putonghua – but in specific rural areas a local interpreter will have a easier time – of course, that’s only if their english (or whatever your mother language is) have the same level. For a text translation it is different: when requesting a translation in Chinese, you will often be asked if you want it in Simplified or Complicated (or Traditional) Chinese, or even Cantonese (also called Yue) – complicated Chinese uses different characters, so even a text translation will be different, while Cantonese is so different from the standard language that even a text translation may be hard to understand for who doesn’t know the language.
We always advise to use Simplified Chinese, unless you have a key interest in areas where Complicated Chinese (Taiwan) and Cantonese (Guangdong, Hong Kong and part of Guangxi) are used. Most of people who understand Complicated Chinese and Cantonese will anyway understand Simplified Chinese, so it would be a favor, but not strictly needed.
For the voice it is completely different: lately more types of Chinese dialects are getting popular, and many apps are getting voice translation even in minor dialects in order to be understood by low education elder users: a remarkable and successful strategy.
For this reason, while we always advise Simplified Chinese combined with Putonghua pronunciation, you may want to provide something more special to your customers – depending on who they are and where they are from, this can be a very good idea, and the extra attention given by a translation in the regional dialects of your customers will have a huge impact on them.