How is hereditary angioedema different from angioedema due to ACE inhibitors?

a) Hereditary angioedema is associated with abdominal pain; ACE inhibitor-induced angioedema is not
b) ACE inhibitor-induced angioedema is not associated with itching; Hereditary angioedema is
c) Both conditions are triggered by allergens
d) There is no difference; the two conditions are identical