self-contained vs self-possessed

self-contained and self-possessed both are adjectives.

Word	Noun	Adjective	Verb	Adverb
self-contained	No	Yes	No	No
self-possessed	No	Yes	No	No

As adjectives, self-contained and self-possessed are synonyms defined as:

Other synonyms of self-contained include collected, equanimous, poised, self-collected.

self-contained (adjective)	self-possessed (adjective)
constituting a complete and independent unit in and of itself	in full control of your faculties
in full control of your faculties