GLFW is a free, Open Source, multi-platform library for opening a window, creating an OpenGL context and managing input
The [Open]GL Utility Toolkit (GLUT) is a utility library for OpenGL applications to put the platform-dependent details (e.g
"Or if you re really focused on only doing opengl i may suggest using glfw which is the better glut but you ll have to draw the menus yourself using opengl"
from question "How to make a menu pop up after mouse release"
"Between these glfw is much closer to glut in character -- a small toolkit for abstracting away most of the os-dependent parts so you can produce opengl programs with relatively little hassle"
from question "How to start developing with OpenGL and C++, what tools do I need to install on windows"