[wmil]

There's no simple standard one, but there are a lot of solutions. The most basic is that MS Word can open two files and show you the differences.

Then there are various "document management systems". Sharepoint has a lot of features for revision tracking. There are multiple Salesforce based solutions.

So there are plenty of products in that market. I don't know if any of them are good. Sharepoint usually works well if you're already using Active Directory.