leak vs leak out

leak is a noun but leak out is not a noun.

Word	Noun	Adjective	Verb	Adverb
leak	Yes	No	Yes	No
leak out	No	No	Yes	No

As verbs, leak and leak out are synonyms defined as:

leak (noun)	leak out (noun)
unauthorized (especially deliberate) disclosure of confidential information
the discharge of a fluid from some container
an accidental hole that allows something (fluid or light etc.) to enter or escape
a euphemism for urination
soft watery rot in fruits and vegetables caused by fungi

leak (verb)	leak out (verb)
have an opening that allows light or substances to enter or go out	be leaked
enter or escape as through a hole or crack or fissure
tell anonymously
be leaked