What is the difference between xml and xml v2 in the file types?

Question

What is the difference between xml and xml v2 in the file types? 
 
 XML file type documentation: 
 docs.sdl.com/.../xml--non-xliff- 
 XML v2 file type documentation: 
 docs.sdl.com/.../xml-v2--non-xliff- 
 EDIT: 
 Found this question 
 https://community.sdl.com/product-groups/translationproductivity/f/studio/29786/what-are-the-advantages-of-the-xml2-file-type-versus-the-xml-embedded-content-file-type 
 
 Comparing the 2 different versions of the DITA file type, I notice the user settings UI has changed a bit, and entity conversion is on by default and has a few new features such as ignoring conversion in locked content. Also, Studio 2021 uses v2 by default while 2019 uses the older version. Other than that, there doesn't seem to be any other differences.

Paul · Answer

Jesse Good 
 Good questions! In fact there are big differences between XML and XML v2 but to be honest I have no clue what we are referring to in the documentation. Tagging Catalina Adam who may be able to clarify.

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What is the difference between xml and xml v2 in the file types?