Speaking from what I know and have read, the Chinese govt. keeps things intentionally ambiguous and doesn't directly apply censorship on Chinese web apps and mobile apps like Wechat unless there is something critical or someone popular is saying censored words. They however do issue instructions and specific lists of social and political keywords that need to be censored, although as noted by Citizen Lab, content critical of the govt. can still exist which keeps things confusing.

Thus, what the Chinese govt. does instead is that they expect the companies to self-censor by hiring their own censorship department or content moderation department that includes political censorship to meet the Chinese govt.'s censorship rules. As well, adding to this, the Chinese govt. usually only establishes ambiguous guidelines that encompass wide range of things like can not offend "Chinese culture" or "Socialist values" so that companies usually over-enforce and over-censor to make sure they don't get fined or their operating licence revoked. Essentially if they get fined or punished, either the app/website shuts down because they can't meet the censorship standards or they remove the users creating the offending material or change a lot of things until they meet censorship standards (although they or the users involved would likely still be "banned" for several years to make an example).

Citizen Lab also points out that censored keywords on different Chinese corporate internet platforms differ likely due to the company's own approach and censorship department. Quote: "We compare our dataset to previously extracted keyword data from chat applications used in China and find very limited keyword list overlap within SVPs and between other platforms. This result substantiates previous findings that suggest companies are only given general directives from authorities and have a degree of flexibility in the implementation."

Thus the difference in the documents could largely be explained by the fact that open-source projects from developers and companies follow the same standards where company employees/content moderators or volunteer moderators compile their own lists or the lists are compiled depending on company or organization policy and purpose. Likely because these organizations do not want to be fined or shut down due to breaking censorship.

References: http://www.indexoncensorship.org/2010/10/china-the-art-of-ce...

https://citizenlab.ca/2015/08/every-rose-has-its-thorn/

https://www.sixthtone.com/news/1003390/for-chinas-web-platfo...

https://citizenlab.ca/2015/06/jason-q-ng-on-chinas-censorshi...

https://www.sixthtone.com/news/1003310/the-people-paid-to-he...

http://www.sixthtone.com/news/751/internet-star-papi-jiang-c...

https://citizenlab.ca/2018/08/cant-picture-this-an-analysis-...

http://www.sixthtone.com/news/1000440/chinas-online-multimed...

https://www.theregister.co.uk/2004/06/21/china_pact/

https://citizenlab.ca/2013/07/using-the-china-chats-surveill...

http://www.sixthtone.com/news/1001621/chinese-people-trust-t...