not the easiest thing i find to think about or clarify but ... i'll try!

this is the way i think about it, though not sure if "technically" or academically this is correct.

Protraction - your upper cervical spine is in extension. Try it - stick your chin out and sit badly (slumped). Lower cervical spine is in flexion.

Retraction - is opposite to protraction. Relative to neutral position, the upper cervical spine is in flexion, and lower cervical in extension .

maybe someone else can back me up on that. hope that helps!