abnormal psychology vs psychopathology

abnormal psychology and psychopathology both are nouns.

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

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

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

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