Difference between jl_get_binding and jl_module_globalref

Hello, I am again a little lost in the masses of the Julia source code.

I have found the functions jl_get_binding and jl_module_globalref and I am a little confused about their difference. The latter does not return a binding, but a value. How can that be a reference, then? If it is not, then how does it differ from jl_get_global?

Thanks for the help!