C++14 was pretty much a patch to C++11.
Stroustrup: ”C++14 is simply the completion of the work that became C++11. When you finish a huge project, there are things you know need to be done, but you can’t add them if you want to ship on time. Inevitably, there are refinements that you don’t realize you need until you can try the whole “product” for real. C++14 adds such features and refinements to C++11.”
From https://www.electronicdesign.com/dev-tools/bjarne-stroustrup-talks-about-c14
See also http://www.drdobbs.com/cpp/the-c14-standard-what-you-need-to-know/240169034