psychopathology vs abnormal psychology

psychopathology and abnormal psychology both are nouns.

Word	Noun	Adjective	Verb	Adverb
psychopathology	Yes	No	No	No
abnormal psychology	Yes	No	No	No

As nouns, psychopathology and abnormal psychology are synonyms defined as:

psychopathology and abnormal psychology: the branch of psychology concerned with abnormal behavior

psychopathology (noun)	abnormal psychology (noun)
the branch of medicine dealing with the diagnosis and treatment of mental disorders	the branch of psychology concerned with abnormal behavior
the branch of psychology concerned with abnormal behavior