VSCode is just a text editor. VEXCode is an IDE and a VEX programming API.
I believe VEXCode supports c++98 unless specified.
PROS is an VEX programming API that comes with a default editor. You can use any editor you want with PROS such as VSCode. PROS provides a command line interface for compiling and uploading to the V5.
PROS uses c++17. PROS also provides some additional libraries such as OkapiLib and is the most open, flexible, expandable, and customizable platform.
Edit:
VEXCode is c++98 not c++11.