infantile fixation vs arrested development

infantile fixation and arrested development both are nouns.

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

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

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

Other synonyms of infantile fixation include fixation, regression.

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