The Glenoid fossa is so called when is not surrounded by the
Glenoid labrum (which increases its depth and also increases the
surface of contact with the head of the humerus). In a specimen (or
in a human body) the glenoid labrum is present, therefore the
Glenoid fossa is called Glenoid cavity (deeper). Basically the
difference is in the presence of the glenoid labrum... not really
the same thing.
Anatomy/Pathology Student