I'm currently working on Magento 2.2. And found that In Magento 2.2 core team made many changes in files and folder structure, deleted many files, replaced classes and many other things.
One other important change found, that in Magento 2.2 generation folder location changed
Change location from
Added new folder metadata in generated folder what is use of it?
Other things found that add new i18n folder at
magento22/app like Magento 1
Does anyone has found more changes or differences in Magento 2.2?