arrested development vs infantile fixation

arrested development and infantile fixation both are nouns.

Word	Noun	Adjective	Verb	Adverb
arrested development	Yes	No	No	No
infantile fixation	Yes	No	No	No

As nouns, arrested development and infantile fixation are synonyms defined as:

arrested development and infantile fixation: an abnormal state in which development has stopped prematurely

Other synonyms of arrested development include fixation, regression.

arrested development (noun)	infantile fixation (noun)
an abnormal state in which development has stopped prematurely	an abnormal state in which development has stopped prematurely