What are the differences between -std=c++17, -std=c++0x and -std=c++1x and why does codeblocks have two same compiler flags? [duplicate]

In Learncpp.com I found that c++1x is the code name of c++11. And When I noticed Code::blocks IDE compiler flags, I saw that it uses the c++0x as coming C++ language standard of C++ 11. Then I noticed that Code::blocks have both -std=c++11 and -std=c++0x compiler flags in compiler flags option. If -std=c++11 and -std=c++0x are same then why there there two flags instead of one. And if -std=c++11 and -std=c++0x are not same and -std=c++1x is similar to -std=c++11, then what about -std=c++14 and -std=c++1y? Why are there two different flags when both are same? That's why I asked that, "What are the differences between -std=c++11, -std=c++0x and -std=c++1x?"