Difference between apprehension and anxiety

[MSNce1]

Explaining the difference between anxiety and depression is more challenging than explain fear versus anxiety. I have a case study for teaching mental health which noted General Anxiety Disorder (GAD) includes excessive anxiety and "apprehensive expectation". I understand anxiety or fear as both disabled emotional reactions while apprehension is more of a cognitive perception there is something to react to in the first place. I invite discussion on this.